[Effects of preexisting donor-specific HLA antibodies for graft failure in un-manipulated haploidentical hematopoietic stem cell transplantation]

Objective: To investigate the effects of donor-specific HLA antibodies(DSA) for graft failure in un-manipulated haploidentical hematopoietic stem cell transplantation(haplo-HSCT) and the feasible treatment for DSA. Methods: HLA antibodies were examined using the Luminex-based single Ag assay for 92 patients who were going on haplo-SCT and the correlations of graft failure and DSA among the patients who had finished SCT were analyzed. Results: Of the total 92 patients who were going on haplo-HSCT, sixteen (17.4%) patients were HLA Ab-positive, including six (6.5%) patients with antibodies corresponding to donor HLA Ags (DSA-positive). Among the patients who had finished the haplo-HSCT with conventional myeloablative conditioning regimen, the engraftment rate was significantly higher in DSA (-) patients than that in DSA (+) patients [92.3% (24/26) vs 25.0%(1/4), χ²=8.433, P=0.004] and DSA was the only factor relevant with graft failure in multiple-factor analysis [OR=12.0(95% CI 1.39-103.5), P=0.024]. Strategies to decrease antibody levels were taken for 4 patients, two were their first transplantations, and the other two patients were their second haplo-HSCT. Three of the four patients were HLA-I-DSA positive and had gained donor engraftment by means of donor platelet transfusions to decreased the level of DSA, the fourth patient with both HLA-I and HLA-II DSA also gained engraftment with the treatments of TBI, rituximab and donor platelet transfusion. Conclusion: DSA is one of the key factors of graft failure in haplo-HSCT. Donors should be selected on the basis of an evaluation of HLA antibodies before transplantation. If haplo-HSCT from donors with DSA must be performed, then recipients should be treated for DSA to improve the chances of successful engraftment.