Human platelet antigen systems in allogeneic peripheral blood progenitor cell transplantation: effect of human platelet antigen mismatch on platelet engraftment and graft-versus-host disease.
BACKGROUND: Alloimmune incompatibility in allo-geneic stem cell transplantation (ASCT), pregnancy, and blood transfusion might trigger an immune response with clinical consequences. Human PLT antigens (HPAs), which play a significant role in pregnancy or blood transfusion-associated alloimmune thrombocytopenia, are also expressed on the surface of tissues affected by GVHD. Thus, HPA mismatch in HLA-identical ASCT could play a potential role in PLT engraftment and GVHD. STUDY DESIGN AND METHODS: We studied the HPA-1, -2, and -5 genotypes in Caucasian donors and patients involved in 77 HLA-identical ASCTs. We evaluated the association of HPA compatibility with clinical outcome, analyzing the relevance of host-versus-donor HPA incompatibility in PLT engraftment and donor-versus-host HPA incompatibility in GVHD. RESULTS: PLT engraftment and transfusion require-ments were similar in HPA-compatible and HPA-incompatible ASCT. Cases with severe thrombocytopenia or significant delayed PLT engraftment did not display host-versus-donor HPA incompatibility. Moreover, the incidence of GVHD did not correlate with HPA compatibility. CONCLUSION: Our results support no role for these antigens in immune complications of ASCT: PLT engraftment, requirement of PLT transfusions, and GVHD.