The Influence of Human Plateley Antigen Match on the Success of Stem Cell Transplantation after Myeloablative or Reduced-Intensity Conditioning Regimen.

Background: Mismatches between donor and recipient for human platelet antigens (HPA) may affect the success of transplantation due to: a) serving as minor histocompatibility antigens and therefore render recipients at risk for GvHD, b) inhibition of thrombopoiesis due to platelet antibodies.

Patients and Methods: We evaluated in 54 patients receiving hematopoietic stem cell transplantation (HSC T) from HLA matched siblings after a myeloablative conditioning regimen the occurrence of GvHD, transplant related mortality (TRM), and the need of platelet support by prospective analyzes of donor-recipient pairs for HPA -1, -2, -3, and -5 allotypes. Patients were screened for platelet antibodies prior to transplantation and in weekly intervals until day 100 after transplantation. Forty five patients receiving HSCT from related or unrelated donors after a reduced-intensity conditioning regimen (RIC) were enrolled retrospectively after a median observation time of 372 days.

Results: Neither the incidence of GvHD and TRM, nor the onset of thrombopoiesis, nor the CCI after platelet transfusions, nor the frequency of platelet transfusions were affected by HPA mismatches. TRM among patients receiving a RIC was higher when grafts were from unrelated donors with 2 or more mismatches. Six of 7 patients who died due to TRM had 2 mismatches in the HPA system, although TRM was not significantly associated with mismatched HPA (p = 0.06). However, within donor-recipient pairs with more than one HPA mismatch TRM occurred when grafts were from unrelated donors (p = 0.03).

Conclusion: Thus, the HPA match does not affect the success of transplantation.