• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of nihpaAbout Author manuscriptsSubmit a manuscriptNIH Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
Br J Haematol. Author manuscript; available in PMC Aug 10, 2011.
Published in final edited form as:
PMCID: PMC3153888
NIHMSID: NIHMS312748

Cytotoxic T lymphocytes as immune-therapy in haematological practice

Summary

Viral infections are a significant cause of morbidity and mortality, particularly in pediatric allogeneic haematopoietic stem cell transplant recipients. Effective therapies are limited and often associated with significant side effects. Adoptive transfer of virus-reactive T cells offers a means of reconstituting antiviral immunity and this approach has been successfully used to prevent and treat cytomegalovirus, Epstein-Barr virus, and adenovirus infections in vivo. This review outlines the clinical trials that have been performed to date, and will describe future initiatives to (a) develop strategies that can increase the breadth of the viruses that can be targeted, and (b) simplify the process to extend this technology to more centers so that cellular therapy to reconstitute immunity can be more widely applied.

Keywords: T cells, stem cell transplantation, viruses, immunotherapy

Hematopoietic stem cell transplantation (HSCT) has evolved into an effective strategy for the treatment of a number of haematological malignancies and many non-malignant disorders. However, successful transplantation of allogeneic hematopoietic stem cells results in immunosuppression until the donor-derived immune system reconstitutes and the duration and severity depends on the type of transplant. As a result, recipients of hemopoietic stem cells are susceptible to a wide array of serious and often lethal opportunistic infections, many of which are not amenable to conventional small-molecule therapeutics.

Increasing numbers of viral pathogens have been implicated in infectious complications after HSCT, partly due to improved diagnostic techniques, increased surveillance, and the discovery of new viruses, and partly as the result of the extension of SCT to higher risk patients who either receive more extensively manipulated products or who require more intensive and prolonged post-transplant immunosuppression. Infections caused by Epstein-Barr virus (EBV), cytomegalovirus (CMV), and herpes simplex virus (HSV), as well as by respiratory viruses, such as Respiratory Syncitial Virus (RSV), parainfluenza, and influenza are well known, while the importance of infections caused by adenovirus (Adv), BK virus, human herpesvirus (HHV)-6, and metapneumoviruses has been more recently appreciated (Flomenberg et al, 1994; Boeckh et al, 2003, 2005; Leen & Rooney, 2005; Martino et al, 2005; Myers et al, 2005; Zerr et al, 2005; Egli et al, 2007; Ison, 2007; Peck et al, 2007; Giraud et al, 2008). Antiviral drugs, which are standard therapy for some infections, are costly short-term control measures that are frequently ineffective and toxic and can induce drug-resistance. In contrast, treatment of the underlying problem, namely lack of antigen-specific T cells to control viral reactivations/infections, can offer effective and long-term protective treatment. This consideration has led to development of therapies designed to reconstitute SCT recipients with protective donor-derived virus-specific T cells.

One approach to prevent and treat these opportunistic infections in the SCT setting involves the use of donor leucocyte infusions (DLI), which consist of unmanipulated T cells isolated from the stem cell donor. But although DLI contain virus-specific T-cell precursors with the potential to protect recipients against infections (Hromas et al, 1994; Papadopoulos et al, 1994), their efficacy is limited by the low frequency of specific T cells to many common “acute” viruses (such as RSV, Adv, and parainfluenza), which are increasingly recognized as a substantial cause of morbidity and mortality after SCT compared to the frequency of alloreactive T cells. Such therapy is therefore limited by an unacceptably high risk of graft-versus-host disease (GvHD) (Heslop et al, 1994; MacKinnon et al, 1995).

Consequently, a number of groups have developed strategies to reconstitute virus-specific T cells post-transplant without inducing alloreactivity and these can be divided into two categories; (i) depletion of alloreactive T cells from DLI or (ii) adoptive transfer of selected populations of virus-specific T cells.

Depletion of alloreactive T cells

Initial attempts to reconstitute HSCT recipients with virus-specific T cells using unmodified DLI led to GvHD in a significant number of patients. One strategy to overcome this problem is to selectively tolerize, or specifically remove, recipient-specific alloreactive T cells from donor leucocyte populations thereby enriching for virus-specific cells in the infusion product.

A number of groups have focused on inducing alloantigen-specific immune tolerance of donor T cell populations (Blazar et al, 1998; Zeller et al, 1999), taking advantage of the inhibitory/suppressive characteristics associated with CD4+ CD25+ regulatory T cells (Treg). Human Tregs isolated from the peripheral blood have been shown to suppress alloresponses in mixed lymphocyte reactions (MLR) (Baecher-Allan et al, 2001; Jonuleit et al, 2001; Levings et al, 2001), and similar results have been achieved in the murine system (Taylor et al, 2001; Hoffmann et al, 2002; Kingsley et al, 2002).

To address whether Tregs that constitutively express FOXP3 play a pivotal role in the maintenance of tolerance and the suppression of GvHD in allogeneic HSCT recipients, Rezvani et al (2006) quantitated the coexpression of FOXP3 on CD4+ T cells in 32 donor SCTs infused into human leucocyte antigen (HLA)-matched siblings and examined the incidence of GvHD in recipients. They found that patients who received a SCT with low absolute numbers of FOXP3+ CD4+ T cells were at greater risk of developing GvHD. In addition, in 21 patients with haematological malignancies who received a T cell-depleted allogeneic SCT, they found that patients who developed GvHD had significantly fewer reconstituting FOXP3+ Tregs than those who did not develop GvHD. Thus, they proposed that the selective expansion and infusion of donor Tregs at the time of transplant could reduce the risk of GvHD, without affecting virus-specific T cell activity (Rezvani et al, 2006). To this end, Hoffmann et al (2004) have developed a system for specifically expanding large numbers of functional Tregs ex vivo using cross-linked anti-CD3 and anti-CD28 antibodies together with high dose interleukin 2; thus this approach is actively being investigated as a cell-based therapy to prevent or treat GvHD.

Protocols for the physical depletion of alloreactive T cells have also been investigated as a means to reduce/prevent GvHD in vivo. Most of the published methods rely on the stimulation of donor T cells with recipient-derived APCs to activate the alloreactive T cell component, followed by specific elimination of the activated cells using antimetabolite drugs, photodepletion, or using immunotoxins or magnetic beads to target differentially-expressed cell surface molecules. The majority of groups have depleted alloactivated cells based on their expression of activation markers, including CD69 (Hartwig et al, 2006), CD25 (Andre-Schmutz et al, 2002; Amrolia et al, 2003, 2006; Solomon et al, 2005), CD134 (O · 40) (Ge et al, 2008) and CD137 (41BB)(Wehler et al, 2007), which are upregulated on donor T cells in response to stimulation with recipient cells. Barrett and colleagues have pioneered an approach to selectively deplete alloreactive cells using a TH9402-based photodepletion technique. This process overcomes fluctuations in activation-based surface marker expression as the photodepletion process targets activation-based changes in p-glycoprotein that result in an altered efflux of the photosensitizer TH9402 (Solomon et al, 2005; Mielke et al, 2008). Using this approach, pathogen-specific responses directed against CMV, Adv, Varicella Zoster Virus, HSV, Aspergillus fumigatus, Candida albicans, and Toxoplasma gondii were retained, albeit with a reduced frequency (Perruccio et al, 2008). Alternatively, methotrexate, a US Federal Drug Administration-approved drug used for the therapy of neoplastic diseases, rheumatoid arthritis and psoriasis, has also been proposed as a potential agent of selective allodepletion, and preclinical results have been promising (Sathe et al, 2007).

The initial allodepletion-based clinical studies tested this strategy using a CD25 immunotoxin (IT) to deplete alloreactive T cells ex vivo (Andre-Schmutz et al, 2002; Solomon et al, 2002, 2005; Amrolia et al, 2003, 2006). In two trials, allodepleted cells were administered after haploidentical CD34-selected transplants and in the third after HLA identical sibling transplant (Andre-Schmutz et al, 2002; Solomon et al, 2005; Amrolia et al, 2006). Either recipient peripheral blood mononuclear cells or EBV-transformed lymphoblastoid cell lines were used as a source of alloantigen for stimulation. In all three studies administration of allodepleted T cells produced reconstitution of antiviral immunity without inducing GvHD. These studies indicate that the concept is feasible, and further studies to optimize the process and increase antitumor immunity are underway.

The limitations of current strategies include the time taken (4–6 weeks) to produce autologous EBV-transformed lymphoblastoid cell lines (EBV-LCL) when these cells are used as APC and the limited availability and instability of the clinical grade IT. In addition, as demonstrated in the dose escalation study by Amrolia and colleagues, a threshold number of T cells was required to produce reconstitution, so that accelerated reconstitution of EBV and CMV-specific T cells was seen only after infusion of 105 T cells/kg or more (Amrolia et al, 2006). Since the recovery of donor cells after allodepletion was approximately 10%, achieving sufficient cell numbers for infusion and for quality control assessments of potency, purity, and sterility often necessitated donor leukapheresis, which is not feasible for unrelated stem cell donors. Finally, T cells specific for a majority of pathogens circulate with much lower frequency than those specific for persistent viruses, such as EBV and CMV (Tan et al, 1999; Gillespie et al, 2000); therefore, even higher allodepleted T cell doses will probably be required to provide full spectrum protection.

Infusion of virus-specific cytotoxic T lymphocytes (CTL)

In vitro reactivation and expansion of virus-specific CTL

As viral complications in transplant recipients are clearly associated with the lack of virus-specific cellular immune responses (Cwynarski et al, 2001; Gottschalk et al, 2005), reconstitution of the host with in vitro expanded virus-specific CTLs is an attractive option to prevent and treat these diseases. In addition, infusion of in vitro expanded virus-specific T cells should be safe, because the prolonged expansion protocol needed to selectively increase the small numbers of virus-specific T cells present in peripheral blood mononuclear cells (PBMC) should also serve to eliminate residual alloreactive T cells from the final infusion product. However, the design of successful immunological strategies to treat human virus-associated diseases and malignancies requires an understanding of the effector processes that control viral infection and the mechanisms viruses use to evade such responses. To date, only a limited number of viruses have been sufficiently well characterized to allow targeting by CTL therapy (Table I).

Table I
Clinical trials using virus-specific cytotoxic T cells post-HSCT.

EBV-specific CTL

We and others have prepared donor-derived EBV CTL, whose infusion prevented and treated EBV-driven B cell lymphoproliferative diseases (EBV-LPD) after allogeneic HSCT (Rooney et al, 1995, 1998; Heslop et al, 1996; Gustafsson et al, 2000). Malignant B cells usually express the complete panel of EBV latent viral antigens, as well as abundant co-stimulatory molecules. Thus, they are highly immunogenic, and are eliminated by circulating EBV-specific CTL in healthy individuals. However, prior to the development of effective pharmacological agents, such as Rituximab which targets the EBV-infected B cells (Kuehnle et al, 2000), the incidence of EBV lymphoproliferation in patients receiving a T cell-depleted graft from an unrelated or HLA-mismatched, related donor, was high (ranging from 1% to 25%). This led our group and others to develop protocols for the in vitro generation of EBV-specific CTLs that could be used as prophylaxis and/or treatment in these high-risk groups.

Since 1993, our group has infused over 65 stem cell recipients with donor-derived EBV-specific T cell lines and established that a dose of 2 · 107 CTL/m2 was safe and efficacious for both prophylaxis and treatment. The methodology we developed, using EBV-LCL to repeatedly stimulate T cells, produced polyclonal CTL lines with CD4:CD8 ratios ranging from 2:98 to 98:2. The first 26 patients enrolled in this study received CTL that were genetically marked with a retroviral vector containing the neomycin resistance gene (neo), allowing the collection of data about the persistence and localization of infused cells in vivo (Rooney et al, 1995; Heslop et al, 1996; Gottschalk et al, 2001; Bollard et al, 2006).

None of the patients treated with EBV-specific CTL as prophylaxis developed PTLD, in contrast with an incidence of 11·5% in a historical untreated control group, and nine patients with elevated EBV-DNA levels at the time of infusion had significantly reduced viral load levels (1–4 log reduction) within 1–3 weeks of the first T cell infusion. In patients who received neo-marked cells, specific CTL could be detected for up to 9 years post CTL. Thus, adoptive immunotherapy was established as an attractive therapy for the prevention and treatment of EBV-LPD in high-risk patients post-transplant. These results have been confirmed by several other groups (Imashuku et al, 1997; Gustafsson et al, 2000; Comoli et al, 2007; O’Reilly et al, 2007).

CMV-specific CTL

Adoptive transfer of in vitro activated and expanded CMV-specific CTL has also been used as prophylaxis and treatment of CMV infections post-transplant. In a pioneering study (Walter et al, 1995), CD8+ CMV-specific T cell clones, reactive against CMV virion proteins, were isolated and expanded from the blood of bone marrow donors and administered to 14 patients prophylactically at weekly intervals in doses escalating from 3·3 · 106/kg to 1 · 109/kg, beginning 30–40 d post-transplant. While the majority of patients lacked any evidence of CMV-specific anti-viral activity preinfusion, after the first infusion responses were detected in all recipients. However, there was no evidence of CD8+ T cell persistence in patients who did not have a concurrent recovery of CD4+ T cells, highlighting the importance of helper T cells in the maintenance of anti-viral activity in vivo. In a number of infused recipients the authors could directly correlate CMV T cell immunity and the persistence (for up to 12 weeks) of transferred T cells by following rearranged TRAV and TRBV genes as molecular markers. Neither CMV viremia nor disease developed in any of the treated patients.

Peggs et al (2003) used a slightly different approach to prevent and treat CMV infections post allogeneic HSCT by producing and characterizing polyclonal CMV-specific CTL using DCs pulsed with CMV antigens derived from a CMV-infected human lung fibroblast cell line to stimulate reactive T cells. Sixteen patients with CMV infection were infused with CMV-specific CTL (1 · 105 CTL/kg) at a median of 36 d post-transplant. The authors were able to reconstitute immunity without inducing GvHD after infusion of relatively small doses of cells because they obtained impressive in vivo expansion of the adoptively-transferred cells, and in eight cases further antiviral drugs were not required (Peggs et al, 2003).

Einsele and colleagues have used polyclonal CMV-specific CTL lines, generated using CMV lysate to activate both CD4+ and CD8+ T cells, as treatment for HSCT patients with persistent or recurrent CMV infections despite the prolonged use of anti-viral medications (Einsele et al, 2002a,b). CTL infusions were effective in reducing the viral load in seven of eight treated individuals and the results were sustained in five, and transient in two patients (Einsele et al, 2002b). Thus, the adoptive transfer of donor-derived CMV-specific T cells is capable of reconstituting immune responses against this virus, and protecting patients against the development of CMV disease or late recurrences.

To avoid the use of lysate or CMV antigen for T cell stimulation, another group adoptively transferred donor-derived CMV peptide-specific T cells to adult and pediatric transplant recipients who had mostly undergone non-myeloablative HSCT without in vitro or in vivo T cell depletion (Foster et al, 2004; Micklethwaite et al, 2007). The adoptively-transferred T cells were activated and expanded using dendritic cells pulsed with the immunodominant CD8+ HLA-A2 restricted epitope NLVPMVATV derived from pp65. In six of nine patients who received T cells there was evidence of an increase in the frequency of specific T cells postinfusion, but the rises were modest and did not persist beyond several days to weeks, which may again be related to lack of CD4+ T cell help. Two of nine patients reactivated CMV, one while receiving high-dose corticosteroids. In the other patient, the reactivation was short and self-limiting. Three patients developed GvHD within 14 d of receiving CMV-specific T cells and one patient died of GvHD. Since all had had GvHD prior to infusion, and the incidences of GvHD coincided with a reduction in corticosteroid dosage, it is unclear whether these recurrences were related to the T cells but the possibility that the T cells may have caused or exacerbated GvHD is a concern.

The residual alloreactive potential of the cells will be more carefully assessed in a follow-up study from the same group using dendritic cells transduced with an adenoviral vector expressing the full length pp65 antigen to reactivate polyclonal CD4+ and CD8+ T cells against multiple different epitopes for infusion purposes. This will overcome the limitations of the previous study which included (a) restriction of treatment to HLA-A2 positive patients, (b) the administration of CTL lines with single peptide specificity, and (c) lack of CD4+ T cell help in the infusion product.

Trivirus-specific CTL

More recently, we have produced bivirus- and trivirus-specific CTL lines containing polyclonal antigen-specific CTL targeting EBV and Adv, or EBV, CMV, and Adv, respectively. The CTL lines were generated by genetically modifying monocytes and EBV-LCL with a chimeric adenoviral vector that was either not expressing a transgene (for the generation of bivirus-specific CTL), or an adenoviral vector expressing CMV-pp65 as a transgene. The EBV-LCL served as the source of EBV antigens, while the adenoviral vector stimulated Adv-specific T cells, and pp65 was used to activate CMV-pp65-specific T cells. Using this protocol we were able to consistently activate and expand CTL lines with the appropriate specificities (Leen et al, 2006).

When small total numbers of trivirus-specific CTL (ca 2 · 105/kg) were administered to allogeneic HSCT recipients receiving a graft from any donor who was EBV and CMV seropositive, the infused cells could expand in vivo and appeared able to protect against all three viruses (Leen et al, 2006). Similar results were achieved when bivirus-specific CTL targeting EBV and Adv were administered to patients receiving a graft from a CMV seronegative donor (unpublished observations). Thus, by administering CTL lines targeting multiple viruses simultaneously, broad spectrum treatment from a single infusion of cells could be offered.

The T cell immune response to Adv is less well understood than that directed against either EBV or CMV(Flomenberg et al, 1995; Smith et al, 1996; Hamel et al, 2002; Leen et al, 2004a,b; Tang et al, 2004, 2006; Veltrop-Duits et al, 2006). Therefore we sought to extensively characterize the Adv-specific T cell component present in the bivirus- and trivirus-specific CTL lines in order to identify the specificities of T cell responses directed against the adenoviral capsid hexon antigen. In total, we screened 26 CTL lines produced for clinical use (13 bivirus and 13 trivirus lines) using a peptide library spanning the entire sequence of the hexon protein (Leen et al, 2006, 2008). Of the 26 lines screened, 25 contained an Adv-specific T cell component, and we confirmed the responsiveness of these CTL lines to previously published epitopes as well as identifying 33 new CD4-and CD8-restricted hexon epitopes. However, there were significantly fewer Adv epitope-specific responses in the trivirus-specific CTL lines generated using the Ad5f35pp65 vector than in the bivirus-specific CTLs generated using the Ad5f35null vector. Thus, it appears that “antigenic competition” can limit the range of antigens/epitopes recognized, and that triviral specificity in a single line seems to be close to the limit of viral-target recognition by the immune system. Thus, extending multivirus-specific CTL therapies to include specificity for and protection from additional viruses may prove problematic, especially for infection with “acute” viruses (e.g parainfluenza and RSV) for which low frequencies of reactive memory T cells circulate in peripheral blood.

Overcoming the limitations of CTL immunotherapy

Although the clinical trials outlined above have all shown promise in the clinical setting, this type of adoptive immunotherapy has been confined to centres with specialized Good Manufacturing Practice (GMP) laboratories. There are three main reasons for this; (i) the complexity of the process and length of time required for the in vitro expansion of virus-reactive T cells, (ii) the limited breadth of viruses that can be targeted in a single CTL line, and (iii) lack of facilities for T cell preparation.

Rapid selection protocols

The time required for complicated CTL generation protocols is one issue that limits broader application of strategies to reconstitute antiviral immunity. Currently, the generation of EBV-, bivirus-, and trivirus-specific CTL lines requires 4–6 weeks to generate EBV-LCL for use as antigen presenting cells (APCs), followed by 4–6 weeks to produce sufficient CTLs for infusion, sterility testing, and functional analysis. Other protocols require the use of dendritic cells (DCs) as APCs, however their generation is also time consuming, and DCs are unable to proliferate in vitro. Consequently large blood volumes are required to produce sufficient DCs for CTL expansion, and therefore cell numbers can be limiting. In addition, each reagent needed for the generation of a CTL line must be available as a clinical grade product, necessitating extensive and expensive analysis and testing.

Although viral infections are frequently evident in patients early post-transplant (<30 d), due to the length of time required for CTL generation, most CTL lines must be prophylactically rather than therapeutically produced. However, if more rapid techniques for CTL production were available or if accurate methods for disease prediction were developed, then CTL therapy could be applied as standard of care rather than as an investigational therapy. Several groups have been developing more rapid and less cumbersome methods to produce virus-specific T cells for infusion (Feuchtinger et al, 2004, 2006; Rauser et al, 2004; Cobbold et al, 2005; Fujita et al, 2008). Two methods have been used clinically; tetramer selection and interferon-γ (IFN-γ) selection, and the studies confirmed that small numbers of antigen-activated T cells could expand substantially in vivo in the presence of antigen, and provide protection against the targeted pathogen.

Tetramer selection

Cobbold and colleagues attempted to decrease the complexity of in vitro CTL generation by isolating a pure population of CMV peptide-specific CD8+ T cells directly from donor peripheral blood using staining with specific tetramers followed by selection with magnetic beads (Cwynarski et al, 2001; Cobbold et al, 2005). This process facilitates the selection and direct infusion of a virus-specific population of cells without ex vivo manipulation, allowing the therapeutic rather than prophylactic use of isolated CTL.

Small numbers (median 8·6 · 103/kg) of selected cells were infused to nine patients within 4 h of selection and, despite small starting cell numbers, CMV-specific CD8+ T cells were detectable in all patients within 10 d of infusion. Further, T cell receptor clonotype analysis showed evidence of persistence in two patients studied. The infused T cells also demonstrated antiviral activity in vivo, particularly in the case of one of the patients whose CMV reactivation was refractory to antiviral drugs, but was controlled within 8 d of adoptive T cell transfer.

Although this study was extremely promising, it has not been reproduced due to the increased regulatory constraints that have been applied to translational laboratories regarding the use of clinical grade reagents. To date, multimers have not been produced to these GMP standards, limiting their use. In the future, GMP grade products may be available, but additional challenges remain including the limited number of CD4+ multimers available. Also, this approach is limited to patients who express HLA alleles for which viral peptides are available and for which the circulating frequency of reactive T cells in peripheral blood is detectable by multimer staining. Thus, infections associated with viruses where the circulating frequency of reactive T cells is much lower than for CMV, will not be amenable to this type of therapy.

IFN-γ capture

The IFN-γ Capture Assay is designed for the quantification and specific isolation of live antigen-stimulated IFN-γ secreting T cells. This technology has been used to rapidly and specifically isolate donor-derived Adv-specific T cells for infusion purposes (Feuchtinger et al, 2004, 2005, 2006). In a pilot study, virus-specific T cells were isolated and infused into nine children with systemic Adv infection after SCT following a short in vitro stimulation with adenoviral antigen. The selected cells were polyclonal, and the infusion of small numbers (1·2–50 · 103/kg) was safe, with no acute toxicities or GvHD induction. In five of six evaluable patients, there was an increase in AdV-specific T cells postinfusion which correlated with a decrease in viral load.

Thus, this approach was feasible, GMP-compatible, and could easily be applied to other infectious pathogens where a source of clinical grade antigen was available. However, although this method of T cell selection was rapid, cells with specificity to only a single virus were produced. Moreover, because of the small numbers of cells selected, it was not possible to characterize the infused product, making it difficult to correlate the phenotype and functional activity of the infused cells with subsequent clinical outcome.

Our group has tried to overcome these shortcomings by merging our trivirus-specific CTL generation technology with the IFN-γ Capture assay to rapidly and specifically isolate antigen-specific T cells directed against EBV, CMV, and Adv for immediate infusion. Further, we have developed a protocol to simultaneously expand a small portion of the selected product using autologous feeder cells and a cocktail of cytokines. This in vitro expansion of small numbers of selected cells facilitates extensive in vitro characterization of the infusion product, allowing us to correlate clinical outcome with the infused cells (Fujita et al, 2008).

These preliminary studies have shown that virus-specific T cells isolated by either tetramer selection or IFN-γ capture are safe and have activity when adoptively transferred to patients with active infection. However both methods rely on the availability of relatively large blood volumes (leukapheresis products), which are difficult to collect from unrelated donors recruited through national or international panels.

Targeting additional viruses

As discussed above, CTL lines that simultaneously target three different viruses have been used clinically with promising results. However, extending this technology to additional pathogens requires (a) extensive immunological characterization to identify immunogenic and protective antigens that can be targeted using T cell therapy, and (b) development of protocols to allow the generation of multivirus-specific CTL lines without loss of antigen specificity due to competition.

A number of groups have begun to analyze the protective immune response directed against community viruses, such as BK virus, RSV and influenza, in order to identify immunogenic antigens that can be targeted using in vitro generated CTL (McMichael et al, 1981; Gotch et al, 1987; Co et al, 2008). The problem of sustained multivirus specificity is also being addressed, and one way to avoid in vitro antigenic competition may involve the prevention of activation-induced cell death (AICD). Vella et al (1997, 1998) reported that the addition of cytokines, such as IL-7 and IL-15, prevented AICD in vitro, and current initiatives involve modifying CTL generation protocols to incorporate these cytokines and the assessment of the specificity, phenotype, and function in the resultant lines.

Partially-matched allogeneic lines

Crawford and colleagues used a different strategy to provide a rapidly available product by generating a bank of polyclonal EBV CTL lines for the treatment of EBV-associated diseases in SCT and solid organ transplant recipients. In a pilot study, eight patients with progressive PTLD were treated with closely HLA-matched CTL generated from an unrelated third-party blood donor (Haque et al, 2002). In the original trial, three patients attained complete remission following treatment, and no patient showed evidence of GvHD postinfusion. More recently, the same group has reported a larger phase 2 multicentre trial, treating 33 patients with EBV positive PTLD that had failed conventional therapy. The CTL lines for infusion were chosen based on the best-fit HLA match with the patient, and the results were encouraging with an overall response rate of 64% at 5 weeks, and 52% at 6 months (Haque et al, 2007).

The 33 PTLD patients treated in this trial were enrolled from 19 transplantation centres, who requested the best matched “off the shelf” product. Due to the partial HLA matching of the CTL used in the trial the authors expected limited persistence of the CTL in vivo. Therefore, to counteract this, 30 of the 33 treated patients received ≥2 CTL infusions. Overall, only one patient developed detectable anti-alloantibodies directed against non-shared HLA antigens, but no patient developed GvHD post-CTL infusion, demonstrating the safety of this approach. Importantly, the authors reported a significant increase in response rate with increased number of HLA matches between CTL donor and recipient (Haque et al, 2007).

Based on these encouraging results, our group has developed a similar multicentre approach to evaluate whether trivirus-specific CTL lines, generated at our centre, can have similar activity. We will establish a bank of trivirus-specific CTL lines, which will be extensively characterized immunologically, and then frozen in aliquots. Following the identification of a patient with an EBV, CMV, and/or an Adv infection/reactivation post-SCT that is persistent despite standard therapy, we will ship an appropriate CTL line to the treatment centre for immediate infusion. The appropriate CTL line will be chosen based on best HLA match and viral specificity.

CTL generation from seronegative donors

Although the generation of donor-derived virus-specific CTL lines has proven feasible from seropositive donors, production of such lines from seronegative adult donors and from cord blood is more challenging because of the antigen-inexperienced or “naïve’’ status of the T cells (Savoldo et al, 2002; Comoli et al, 2006). However, Park et al (2006) have recently developed an approach for the generation of CMV-specific T cells from cord blood using CMV antigen-loaded DCs to stimulate T cells. Culture in the presence of IL-7 and IL-12 and weekly antigen re-stimulation resulted in the generation of CMV-specific IFN-γ-producing CTL, which were consistently detectable by the fourth week of stimulation. Therefore, although more complicated and time consuming than the seropositive setting, such an approach may eventually lead to effective clinical strategies to prevent or treat opportunistic viral infections in the cord blood transplantation setting (Park et al, 2006). Alternatively, infusion of allogeneic banked CTL, as described above, may also confer protection from viral infections prior to endogenous T cell recovery.

Conclusions

Viral infections post-HSCT are an increasing cause of morbidity and mortality post-transplant. Adoptive immunotherapy to reconstitute antiviral immunity is an attractive prophylaxis and/or treatment option and the focus of a number of groups is to simplify the process to make this option more broadly available for clinical use.

Acknowledgements

AML and HEH are supported by NIH Grants PO1 CA94237, U54HL081007, P50CA126752, the GCRC at Baylor College of Medicine (RR00188), and a Specialized Center of Research Award from the Leukemia and Lymphoma Society, an Infection and Immunity award from Baylor College of Medicine to AML and HEH and a Doris Duke Distinguished Clinical Scientist Award to HEH.

References

  • Amrolia PJ, Muccioli-Casadei G, Yvon E, Huls H, Sili U, Wieder ED, Bollard C, Michalek J, Ghetie V, Heslop HE, Molldrem JJ, Rooney CM, Schlinder J, Vitetta E, Brenner MK. Selective depletion of donor alloreactive T cells without loss of antiviral or antileukemic responses. Blood. 2003;102:2292–2299. [PubMed]
  • Amrolia PJ, Muccioli-Casadei G, Huls H, Adams S, Durett A, Gee A, Yvon E, Weiss H, Cobbold M, Gaspar HB, Rooney C, Kuehnle I, Ghetie V, Schindler J, Krance R, Heslop HE, Veys P, Vitetta E, Brenner MK. Adoptive immunotherapy with allodepleted donor T-cells improves immune reconstitution after haploidentical stem cell transplantation. Blood. 2006;108:1797–1808. [PMC free article] [PubMed]
  • Andre-Schmutz I, Le DF, Hacein-Bey-Abina S, Vitetta E, Schindler J, Chedeville G, Vilmer E, Fischer A, Cavazzana-Calvo M. Immune reconstitution without graft-versus-host disease after haemopoietic stem-cell transplantation: a phase 1/2 study. Lancet. 2002;360:130–137. [PubMed]
  • Baecher-Allan C, Brown JA, Freeman GJ, Hafler DA. CD4+ CD25high regulatory cells in human peripheral blood. Journal of Immunology. 2001;167:1245–1253. [PubMed]
  • Blazar BR, Taylor PA, Noelle RJ, Vallera DA. CD4(+) T cells tolerized ex vivo to host alloantigen by anti-CD40 ligand (CD40L:CD154) antibody lose their graft-versus-host disease lethality capacity but retain nominal antigen responses. The Journal of Clinical Investigation. 1998;102:473–482. [PMC free article] [PubMed]
  • Boeckh M, Nichols WG, Papanicolaou G, Rubin R, Wingard JR, Zaia J. Cytomegalovirus in hematopoietic stem cell transplant recipients: current status, known challenges, and future strategies. Biology of Blood and Marrow Transplantation. 2003;9:543–558. [PubMed]
  • Boeckh M, Erard V, Zerr D, Englund J. Emerging viral infections after hematopoietic cell transplantation. Pediatric Transplantation. 2005;9 Suppl. 7:48–54. [PubMed]
  • Bollard CM, Gottschalk S, Huls MH, Molldrem J, Przepiorka D, Rooney CM, Heslop HE. In vivo expansion of LMP1-and LMP2-specific T-cells in a patient who received donor-derived EBV-specific T-cells after allogeneic stem cell transplantation. Leukemia & Lymphoma. 2006;47:837–842. [PubMed]
  • Co MD, Orphin L, Cruz J, Pazoles P, Rothman AL, Ennis FA, Terajima M. Discordance between antibody and T cell responses in recipients of trivalent inactivated influenza vaccine. Vaccine. 2008;26:1990–1998. [PMC free article] [PubMed]
  • Cobbold M, Khan N, Pourgheysari B, Tauro S, McDonald D, Osman H, Assenmacher M, Billingham L, Steward C, Crawley C, Olavarria E, Goldman J, Chakraverty R, Mahendra P, Craddock C, Moss PA. Adoptive transfer of cytomegalovirus-specific CTL to stem cell transplant patients after selection by HLA-peptide tetramers. The Journal of Experimental Medicine. 2005;202:379–386. [PMC free article] [PubMed]
  • Comoli P, Ginevri F, Maccario R, Frasson C, Valente U, Basso S, Labirio M, Huang GC, Verrina E, Baldanti F, Perfumo F, Locatelli F. Successful in vitro priming of EBV-specific CD8+ T cells endowed with strong cytotoxic function from T cells of EBV-seronegative children. American Journal of Transplantation. 2006;6:2169–2176. [PubMed]
  • Comoli P, Basso S, Zecca M, Pagliara D, Baldanti F, Bernardo ME, Barberi W, Moretta A, Labirio M, Paulli M, Furione M, Maccario R, Locatelli F. Preemptive therapy of EBV-related lymphoproliferative disease after pediatric haploidentical stem cell transplantation. American Journal of Transplantation. 2007;7:1648–1655. [PubMed]
  • Cwynarski K, Ainsworth J, Cobbold M, Wagner S, Mahendra P, Apperley J, Goldman J, Craddock C, Moss PA. Direct visualization of cytomegalovirus-specific T-cell reconstitution after allogeneic stem cell transplantation. Blood. 2001;97:1232–1240. [PubMed]
  • Egli A, Binggeli S, Bodaghi S, Dumoulin A, Funk GA, Khanna N, Leuenberger D, Gosert R, Hirsch HH. Cytomegalovirus and polyomavirus BK posttransplant. Nephrology, Dialysis, Transplantation. 2007;22 Suppl. 8:viii72–viii82. [PubMed]
  • Einsele H, Rauser G, Grigoleit U, Hebart H, Sinzger C, Riegler S, Jahn G. Induction of CMV-specific T-cell lines using Ag-presenting cells pulsed with CMV protein or peptide. Cytotherapy. 2002a;4:49–54. [PubMed]
  • Einsele H, Roosnek E, Rufer N, Sinzger C, Riegler S, Loffler J, Grigoleit U, Moris A, Rammensee HG, Kanz L, Kleihauer A, Frank F, Jahn G, Hebart H. Infusion of cytomegalovirus (CMV)-specific T cells for the treatment of CMV infection not responding to antiviral chemotherapy. Blood. 2002b;99:3916–3922. [PubMed]
  • Feuchtinger T, Lang P, Hamprecht K, Schumm M, Greil J, Jahn G, Niethammer D, Einsele H. Isolation and expansion of human adenovirus-specific CD4+ and CD8+ T cells according to IFN-gamma secretion for adjuvant immunotherapy. Experimental Hematology. 2004;32:282–289. [PubMed]
  • Feuchtinger T, Lucke J, Hamprecht K, Richard C, Handgretinger R, Schumm M, Greil J, Bock T, Niethammer D, Lang P. Detection of adenovirus-specific T cells in children with adenovirus infection after allogeneic stem cell transplantation. British Journal of Haematology. 2005;128:503–509. [PubMed]
  • Feuchtinger T, Matthes-Martin S, Richard C, Lion T, Fuhrer M, Hamprecht K, Handgretinger R, Peters C, Schuster FR, Beck R, Schumm M, Lotfi R, Jahn G, Lang P. Safe adoptive transfer of virus-specific T-cell immunity for the treatment of systemic adenovirus infection after allogeneic stem cell transplantation. British Journal of Haematology. 2006;134:64–76. [PubMed]
  • Flomenberg P, Babbitt J, Drobyski WR, Ash RC, Carrigan DR, Sedmak GV, McAuliffe T, Camitta B, Horowitz MM, Bunin N, Casper JT. Increasing incidence of adenovirus disease in bone marrow transplant recipients. Journal of Infectious Diseases. 1994;169:775–781. [PubMed]
  • Flomenberg P, Piaskowski V, Truitt RL, Casper JT. Characterization of human proliferative T cell responses to adenovirus. Journal of Infectious Diseases. 1995;171:1090–1096. [PubMed]
  • Foster AE, Bradstock KF, Sili U, Marangolo M, Rooney CM, Gottlieb DJ. A comparison of gene transfer and antigenloaded dendritic cells for the generation of CD4+ and CD8+ cytomegalovirus-specific T cells in HLA-A2+ and HLA-A2- donors. Biology of Blood and Marrow Transplantation. 2004;10:761–771. [PubMed]
  • Fujita Y, Leen AM, Sun J, Nakazawa Y, Yvon E, Heslop HE, Brenner MK, Rooney CM. Exploiting cytokine secretion to rapidly produce multivirus-specific T cells for adoptive immunotherapy. Journal of Immunotherapy. 2008 [Epub ahead of print] [PMC free article] [PubMed]
  • Ge X, Brown J, Sykes M, Boussiotis VA. CD134-allodepletion allows selective elimination of alloreactive human T cells without loss of virus-specific and leukemia-specific effectors. Biology of Blood and Marrow Transplantation. 2008;14:518–530. [PMC free article] [PubMed]
  • Gillespie GM, Wills MR, Appay V, O’Callaghan C, Murphy M, Smith N, Sissons P, Rowland-Jones S, Bell JI, Moss PA. Functional heterogeneity and high frequencies of cytomegalovirus-specific CD8(+) T lymphocytes in healthy seropositive donors. Journal of Virology. 2000;74:8140–8150. [PMC free article] [PubMed]
  • Giraud G, Priftakis P, Bogdanovic G, Remberger M, Dubrulle M, Hau A, Gutmark R, Mattson J, Svahn BM, Ringden O, Winiarski J, Ljungman P, Dalianis T. BK-viruria and haemorrhagic cystitis are more frequent in allogeneic haematopoietic stem cell transplant patients receiving full conditioning and unrelated-HLA-mismatched grafts. Bone Marrow Transplantation. 2008;41:737–742. [PubMed]
  • Gotch F, McMichael A, Smith G, Moss B. Identification of viral molecules recognized by influenza-specific human cytotoxic T lymphocytes. The Journal of Experimental Medicine. 1987;165:408–416. [PMC free article] [PubMed]
  • Gottschalk S, Ng CYC, Smith CA, Perez M, Sample C, Brenner MK, Heslop HE, Rooney CM. An Epstein-Barr virus deletion mutant that causes fatal lymphoproliferative disease unresponsive to virus-specific T cell therapy. Blood. 2001;97:835–843. [PubMed]
  • Gottschalk S, Rooney CM, Heslop HE. Post-transplant lymphoproliferative disorders. Annual Review of Medicine. 2005;56:29–44. [PubMed]
  • Gustafsson A, Levitsky V, Zou JZ, Frisan T, Dalianis T, Ljungman P, Ringden O, Winiarski J, Ernberg I, Masucci MG. Epstein-Barr virus (EBV) load in bone marrow transplant recipients at risk to develop posttransplant lymphoproliferative disease: prophylactic infusion of EBV-specific cytotoxic T cells. Blood. 2000;95:807–814. [PubMed]
  • Hamel Y, Blake N, Gabrielsson S, Haigh T, Jooss K, Martinache C, Caillat-Zucman S, Rickinson AB, Hacein-Bey S, Fischer A, Cavazzana-Calvo M. Adenovirally transduced dendritic cells induce bispecific cytotoxic T lymphocyte responses against adenovirus and cytomegalovirus pp65 or against adenovirus and Epstein-Barr virus EBNA3C protein: a novel approach for immunotherapy. Human Gene Therapy. 2002;13:855–866. [PubMed]
  • Haque T, Wilkie GM, Taylor C, Amlot PL, Murad P, Iley A, Dombagoda D, Britton KM, Swerdlow AJ, Crawford DH. Treatment of Epstein-Barr-virus-positive post-transplantation lymphoproliferative disease with partly HLA-matched allogeneic cytotoxic T cells. Lancet. 2002;360:436–442. [PubMed]
  • Haque T, Wilkie GM, Jones MM, Higgins CD, Urquhart G, Wingate P, Burns D, McAulay K, Turner M, Bellamy C, Amlot PL, Kelly D, MacGilchrist A, Gandhi MK, Swerdlow AJ, Crawford DH. Allogeneic cytotoxic T-cell therapy for EBV-positive posttransplantation lymphoproliferative disease: results of a phase 2 multicenter clinical trial. Blood. 2007;110:1123–1131. [PubMed]
  • Hartwig UF, Nonn M, Khan S, Meyer RG, Huber C, Herr W. Depletion of alloreactive T cells via CD69: implications on antiviral, antileukemic and immunoregulatory T lymphocytes. Bone Marrow Transplantation. 2006;37:297–305. [PubMed]
  • Heslop HE, Brenner MK, Rooney CM. Donor T cells to treat EBV-associated lymphoma. New England Journal of Medicine. 1994;331:679–680. [PubMed]
  • Heslop HE, Ng CYC, Li C, Smith CA, Loftin SK, Krance RA, Brenner MK, Rooney CM. Long-term restoration of immunity against Epstein-Barr virus infection by adoptive transfer of gene-modified virus-specific T lymphocytes. Nature Medicine. 1996;2:551–555. [PubMed]
  • Hoffmann P, Ermann J, Edinger M, Fathman CG, Strober S. Donor-type CD4(+)CD25(+) regulatory T cells suppress lethal acute graft-versus-host disease after allogeneic bone marrow transplantation. The Journal of Experimental Medicine. 2002;196:389–399. [PMC free article] [PubMed]
  • Hoffmann P, Eder R, Kunz-Schughart LA, Andreesen R, Edinger M. Large-scale in vitro expansion of polyclonal human CD4(+)CD25high regulatory T cells. Blood. 2004;104:895–903. [PubMed]
  • Hromas R, Cornetta K, Srour E, Blanke C, Broun ER. Donor leukocyte infusion as therapy of life-threatening adenoviral infections after T-cell-depleted bone marrow transplantation. Blood. 1994;84:1689–1690. [PubMed]
  • Imashuku S, Goto T, Matsumura T, Naya M, Yamori M, Hojo M, Hibi S, Todo S. Unsuccessful CTL transfusion in a case of post-BMT Epstein-Barr virus-associated lymphoproliferative disorder (EBV-LPD) Bone Marrow Transplantation. 1997;20:337–340. [PubMed]
  • Ison MG. Respiratory viral infections in transplant recipients. Antiviral Therapy. 2007;12:627–638. [PubMed]
  • Jonuleit H, Schmitt E, Stassen M, Tuettenberg A, Knop J, Enk AH. Identification and functional characterization of human CD4(+)CD25(+) T cells with regulatory properties isolated from peripheral blood. The Journal of Experimental Medicine. 2001;193:1285–1294. [PMC free article] [PubMed]
  • Kingsley CI, Karim M, Bushell AR, Wood KJ. CD25+ CD4+ regulatory T cells prevent graft rejection: CTLA-4- and IL-10-dependent immunoregulation of alloresponses. Journal of Immunology. 2002;168:1080–1086. [PubMed]
  • Kuehnle I, Huls MH, Liu Z, Semmelmann M, Krance RA, Brenner MK, Rooney CM, Heslop HE. CD20 monoclonal antibody (rituximab) for therapy of Epstein-Barr virus lymphoma after hemopoietic stem-cell transplantation. Blood. 2000;95:1502–1505. [PubMed]
  • Leen AM, Rooney CM. Adenovirus as an emerging pathogen in immunocompromised patients. British Journal of Haematology. 2005;128:135–144. [PubMed]
  • Leen AM, Sili U, Savoldo B, Jewell AM, Piedra PA, Brenner MK, Rooney CM. Fiber-modified adenoviruses generate subgroup cross-reactive, adenovirus-specific cytotoxic T lymphocytes for therapeutic applications. Blood. 2004a;103:1011–1019. [PubMed]
  • Leen AM, Sili U, Vanin EF, Jewell AM, Xie W, Vignali D, Piedra PA, Brenner MK, Rooney CM. Conserved CTL epitopes on the adenovirus hexon protein expand subgroup cross-reactive and subgroup-specific CD8+ T cells. Blood. 2004b;104:2432–2440. [PubMed]
  • Leen AM, Myers GD, Sili U, Huls MH, Weiss H, Leung KS, Carrum G, Krance RA, Chang CC, Molldrem JJ, Gee AP, Brenner MK, Heslop HE, Rooney CM, Bollard CM. Monoculture-derived T lymphocytes specific for multiple viruses expand and produce clinically relevant effects in immunocompromised individuals. Nature Medicine. 2006;12:1160–1166. [PubMed]
  • Leen AM, Christin A, Khalil M, Weiss H, Gee AP, Brenner MK, Heslop HE, Rooney CM, Bollard CM. Identification of hexon-specific CD4 and CD8 T-cell epitopes for vaccine and immunotherapy. Journal of Virology. 2008;82:546–554. [PMC free article] [PubMed]
  • Levings MK, Sangregorio R, Roncarolo MG. Human cd25(+)cd4(+) t regulatory cells suppress naive and memory T cell proliferation and can be expanded in vitro without loss of function. The Journal of Experimental Medicine. 2001;193:1295–1302. [PMC free article] [PubMed]
  • MacKinnon S, Papadopoulos EB, Carabasi MH, Reich L, Collins NH, O’Reilly RJ. Adoptive immunotherapy using donor leukocytes following bone marrow transplantation for chronic myeloid leukemia: is T cell dose important in determining biological response? Bone Marrow Transplantation. 1995;15:591–594. [PubMed]
  • Martino R, Porras RP, Rabella N, Williams JV, Ramila E, Margall N, Labeaga R, Crowe JE, Jr, Coll P, Sierra J. Prospective study of the incidence, clinical features, and outcome of symptomatic upper and lower respiratory tract infections by respiratory viruses in adult recipients of hematopoietic stem cell transplants for hematologic malignancies. Biology of Blood and Marrow Transplantation. 2005;11:781–796. [PMC free article] [PubMed]
  • McMichael AJ, Gotch F, Cullen P, Askonas B, Webster RG. The human cytotoxic T cell response to influenza A vaccination. Clinical and Experimental Immunology. 1981;43:276–284. [PMC free article] [PubMed]
  • Micklethwaite K, Hansen A, Foster A, Snape E, Antonenas V, Sartor M, Shaw P, Bradstock K, Gottlieb D. Ex vivo expansion and prophylactic infusion of CMV-pp65 peptide-specific cytotoxic T-lymphocytes following allogeneic hematopoietic stem cell transplantation. Biology of Blood and Marrow Transplantation. 2007;13:707–714. [PubMed]
  • Mielke S, Nunes R, Rezvani K, Fellowes VS, Venne A, Solomon SR, Fan Y, Gostick E, Price DA, Scotto C, Read EJ, Barrett AJ. A clinical-scale selective allodepletion approach for the treatment of HLA-mismatched and matched donor-recipient pairs using expanded T lymphocytes as antigen-presenting cells and a TH9402-based photodepletion technique. Blood. 2008;111:4392–4402. [PMC free article] [PubMed]
  • Myers GD, Krance RA, Weiss H, Kuehnle I, Demmler G, Heslop HE, Bollard CM. Adenovirus infection rates in pediatric recipients of alternate donor allogeneic bone marrow transplants receiving either antithymocyte globulin (ATG) or alemtuzumab (Campath) Bone Marrow Transplantation. 2005;36:1001–1008. [PubMed]
  • O’Reilly RJ, Doubrovina E, Trivedi D, Hasan A, Kollen W, Koehne G. Adoptive transfer of antigen-specific T-cells of donor type for immunotherapy of viral infections following allogeneic hematopoietic cell transplants. Immunologic Research. 2007;38:237–250. [PubMed]
  • Papadopoulos EB, Ladanyi M, Emanuel D, MacKinnon S, Boulad F, Carabasi MH, Castro-Malaspina H, Childs BH, Gillio AP, Small TN, Young JW, Kernan NA, O’Reilly RJ. Infusions of donor leukocytes to treat Epstein-Barr virus-associated lymphoproliferative disorders after allogeneic bone marrow transplantation. The New England Journal of Medicine. 1994;330:1185–1191. [PubMed]
  • Park KD, Marti L, Kurtzberg J, Szabolcs P. In vitro priming and expansion of cytomegalovirus-specific Th1 and Tc1 T cells from naive cord blood lymphocytes. Blood. 2006;108:1770–1773. [PMC free article] [PubMed]
  • Peck AJ, Englund JA, Kuypers J, Guthrie KA, Corey L, Morrow R, Hackman RC, Cent A, Boeckh M. Respiratory virus infection among hematopoietic cell transplant recipients: evidence for asymptomatic parainfluenza virus infection. Blood. 2007;110:1681–1688. [PMC free article] [PubMed]
  • Peggs KS, Verfuerth S, Pizzey A, Khan N, Guiver M, Moss PA, MacKinnon S. Adoptive cellular therapy for early cytomegalovirus infection after allogeneic stem-cell transplantation with virus-specific T-cell lines. Lancet. 2003;362:1375–1377. [PubMed]
  • Perruccio K, Topini F, Tosti A, Carotti A, Aloisi T, Aversa F, Martelli MF, Velardi A. Photodynamic purging of alloreactive T cells for adoptive immunotherapy after haploidentical stem cell transplantation. Blood Cells, Molecules & Diseases. 2008;40:76–83. [PubMed]
  • Rauser G, Einsele H, Sinzger C, Wernet D, Kuntz G, Assenmacher M, Campbell JD, Topp MS. Rapid generation of combined CMV-specific CD4+ and CD8+ T-cell lines for adoptive transfer into recipients of allogeneic stem cell transplants. Blood. 2004;103:3565–3572. [PubMed]
  • Rezvani K, Mielke S, Ahmadzadeh M, Kilical Y, Savani BN, Zeilah J, Keyvanfar K, Montero A, Hensel N, Kurlander R, Barrett AJ. High donor FOXP3-positive regulatory T-cell (Treg) content is associated with a low risk of GVHD following HLA-matched allogeneic SCT. Blood. 2006;108:1291–1297. [PMC free article] [PubMed]
  • Rooney CM, Smith CA, Ng C, Loftin SK, Li C, Krance RA, Brenner MK, Heslop HE. Use of gene-modified virus-specific T lymphocytes to control Epstein-Barr virus-related lymphoproliferation. Lancet. 1995;345:9–13. [PubMed]
  • Rooney CM, Smith CA, Ng CY, Loftin SK, Sixbey JW, Gan Y, Srivastava DK, Bowman LC, Krance RA, Brenner MK, Heslop HE. Infusion of cytotoxic T cells for the prevention and treatment of Epstein-Barr virus-induced lymphoma in allogeneic transplant recipients. Blood. 1998;92:1549–1555. [PubMed]
  • Sathe A, Ortega SB, Mundy DI, Collins RH, Karandikar NJ. In vitro methotrexate as a practical approach to selective allodepletion. Biology of Blood and Marrow Transplantation. 2007;13:644–654. [PubMed]
  • Savoldo B, Cubbage ML, Durett AG, Goss J, Huls MH, Liu Z, Teresita L, Gee AP, Ling PD, Brenner MK, Heslop HE, Rooney CM. Generation of EBV-specific CD4+ cytotoxic T cells from virus naive individuals. Journal of Immunology. 2002;168:909–918. [PubMed]
  • Smith CA, Woodruff LS, Kitchingman GR, Rooney CM. Adenovirus-pulsed dendritic cells stimulate human virus-specific T-cell responses in vitro. Journal of Virology. 1996;70:6733–6740. [PMC free article] [PubMed]
  • Solomon SR, Tran T, Carter CS, Donnelly S, Hensel N, Schindler J, Bahceci E, Ghetie V, Michalek J, Mavroudis D, Read EJ, Vitetta ES, Barrett AJ. Optimized clinical-scale culture conditions for ex vivo selective depletion of host-reactive donor lymphocytes: a strategy for GvHD prophylaxis in allogeneic PBSC transplantation. Cytotherapy. 2002;4:395–406. [PubMed]
  • Solomon SR, Mielke S, Savani BN, Montero A, Wisch L, Childs R, Hensel N, Schindler J, Ghetie V, Leitman SF, Mai T, Carter CS, Kurlander R, Read EJ, Vitetta ES, Barrett AJ. Selective depletion of alloreactive donor lymphocytes: a novel method to reduce the severity of graft-versus-host disease in older patients undergoing matched sibling donor stem cell transplantation. Blood. 2005;106:1123–1129. [PMC free article] [PubMed]
  • Tan LC, Gudgeon N, Annels NE, Hansasuta P, O’Callaghan CA, Rowland-Jones S, McMichael AJ, Rickinson AB, Callan MF. A re-evaluation of the frequency of CD8+ T cells specific for EBV in healthy virus carriers. Journal of Immunology. 1999;162:1827–1835. [PubMed]
  • Tang J, Olive M, Champagne K, Flomenberg N, Eisenlohr L, Hsu S, Flomenberg P. Adenovirus hexon T-cell epitope is recognized by most adults and is restricted by HLA DP4, the most common class II allele. Gene Therapy. 2004;11:1408–1415. [PubMed]
  • Tang J, Olive M, Pulmanausahakul R, Schnell M, Flomenberg N, Eisenlohr L, Flomenberg P. Human CD8+ cytotoxic T cell responses to adenovirus capsid proteins. Virology. 2006;350:312–322. [PubMed]
  • Taylor PA, Noelle RJ, Blazar BR. CD4(+)CD25(+) immune regulatory cells are required for induction of tolerance to alloantigen via costimulatory blockade. The Journal of Experimental Medicine. 2001;193:1311–1318. [PMC free article] [PubMed]
  • Vella A, Teague TK, Ihle J, Kappler J, Marrack P. Interleukin 4 (IL-4) or IL-7 prevents the death of resting T cells: stat6 is probably not required for the effect of IL-4. The Journal of Experimental Medicine. 1997;186:325–330. [PMC free article] [PubMed]
  • Vella AT, Dow S, Potter TA, Kappler J, Marrack P. Cytokine-induced survival of activated T cells in vitro and in vivo. Proceedings of the National Academy of Sciences of the United States of America. 1998;95:3810–3815. [PMC free article] [PubMed]
  • Veltrop-Duits LA, Heemskerk B, Sombroek CC, van VT, Gubbels S, Toes RE, Melief CJ, Franken KL, Havenga M, van Tol MJ, Schilham MW. Human CD4+ T cells stimulated by conserved adenovirus 5 hexon peptides recognize cells infected with different species of human adenovirus. European Journal of Immunology. 2006;36:2410–2423. [PubMed]
  • Walter EA, Greenberg PD, Gilbert MJ, Finch RJ, Watanabe KS, Thomas ED, Riddell SR. Reconstitution of cellular immunity against cytomegalovirus in recipients of allogeneic bone marrow by transfer of T-cell clones from the donor. The New England Journal of Medicine. 1995;333:1038–1044. [PubMed]
  • Wehler TC, Nonn M, Brandt B, Britten CM, Grone M, Todorova M, Link I, Khan SA, Meyer RG, Huber C, Hartwig UF, Herr W. Targeting the activation-induced antigen CD137 can selectively deplete alloreactive T cells from antileukemic and antitumor donor T-cell lines. Blood. 2007;109:365–373. [PubMed]
  • Zeller JC, Panoskaltsis-Mortari A, Murphy WJ, Ruscetti FW, Narula S, Roncarolo MG, Blazar BR. Induction of CD4+ T cell alloantigen-specific hyporesponsiveness by IL-10 and TGF-beta. Journal of Immunology. 1999;163:3684–3691. [PubMed]
  • Zerr DM, Corey L, Kim HW, Huang ML, Nguy L, Boeckh M. Clinical outcomes of human herpesvirus 6 reactivation after hematopoietic stem cell transplantation. Clinical Infectious Diseases. 2005;40:932–940. [PubMed]
PubReader format: click here to try

Formats:

Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...

Links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...