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Ann N Y Acad Sci. 2005 Dec;1062:137-45.

Evaluation of topoisomerase-1-specific CD8+ T-cell response in systemic sclerosis.

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Division of Rheumatology, The Johns Hopkins University School of Medicine, 5200 Eastern Ave., Mason F. Lord Bldg., Center Tower, Ste. 4100, Baltimore, MD 21224, USA.


Measurement of disease activity in systemic autoimmune disorders is often unreliable, and immunosuppressive therapy is often titrated to crude clinical response and/or onset of complications. Systemic sclerosis (SSc) presents a distinct clinical phenotype associated with specific autoantibodies. Anti-topoisomerase-1 (SCL-70) is selectively detected in 30-60% of subjects with diffuse skin and interstitial lung involvement. Such patients offer an ideal clinical model to characterize and quantify the autoantigen-specific T-cell response and its correlation with disease phenotype and activity. Human leukocyte antigen A2 (HLA-A2)-restricted topo-1 peptides were selected based on an epitope prediction algorithm. For initial studies, the best binder topo-1(262-270) KMLDHEYTT (#262) was used alone or loaded onto an artificial antigen-presenting platform generated by coupling a dimeric major histocompatibility complex-immunoglobulin G fusion protein (HLA-A2-Ig) and anti-CD28 antibodies onto magnetic beads (artificial antigen-presenting cells). Blood samples (100 microL) from HLA-A2+ SSc patients and cytomegalovirus (CMV) seropositive healthy control subjects were tested in an intracellular cytokine staining assay. Gamma interferon production by CD8+ T cells was measured after stimulation with peptide #262, CMVpp65, or MART-1 (irrelevant peptide). In two of five SCL-70+ patients, peptide #262-loaded aAPCs induced a specific CD8+ T-cell response (0.45% +/- 0.23% of total CD8+ cells). This response was not observed in the seven SCL-70- (five SSc and two CMV+) control subjects studied (0.03% +/- 0.02%). Interestingly, bronchoalveolar lavage fluid obtained from one topo-1-responsive SSc patient who had worsening respiratory function and active alveolitis showed striking enrichment of topo-1-specific CD8+ T cells (3.94%). This small-volume ex vivo assay may prove to be a sensitive and specific tool to assess disease activity and to monitor response to therapy in patients with scleroderma.

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