Prevalence and risk factors of antibodies to human leukocyte antigens in haploidentical stem cell transplantation candidates: A multi-center study.

We investigated the prevalence of and risk factors for antibodies to HLA in 1663 haploidentical transplant candidates. Among these cases, 349 (21.0%) showed positive panel-reactive antibody (PRA) either for class I or class II HLA. Multivariate analysis showed the following: i) risk factors associated with the prevalence of PRA either for class I or class II HLA were female gender (P = 0.018), prior transfusions (P < 0.001) or pregnancy (P < 0.001), and cases with MDS (P = 0.018); compared to other patients, subjects with ALL had a lower prevalence of class I antibodies (P = 0.017); and ii) risk factors associated with the prevalence of PRA both for class I and class II HLA were female gender (P = 0.014), prior transfusions (P = 0.003), previous pregnancy (P < 0.001), and diagnosis with MDS (P = 0.035). The percentages of antibodies against different antigens coded by the different HLA loci, including HLA-A, -B, -C, -DP, -DQ, and -DR, among all cases were 15.6%, 17.3%, 10.5%, 5.6%, 8.5%, and 9.7%, respectively. Risk factors associated with specific antibodies against HLA-A, -B, -C, -DP, -DQ, and -DR were female gender, prior transfusion, previous pregnancy, and underlying disease. Our findings suggest that gender, prior pregnancy, transfusion and underlying diseases are risk factors for HLA sensitization, which could guide HLA antibody monitor and donor selection.