Sex-specific survival difference in association with HLA-DRB1 *04 following allogeneic haematopoietic stem cell transplantation for lymphoid malignancies

The role of HLA system in allogeneic haematopoietic stem cell transplantation (allo-HSCT) outcome is unarguable. In this study we investigated association of HLA-A,-B and-DRB1 alleles with overall survival (OS) in 186 patients undergoing allo-HSCT for lymphoid malignancies. Analyses confirmed significantly better OS for HLA-DRB1 *04 carriers compared with non-carriers (p=0.01). Survival benefit was confined to male patients (in multivariate analyses p=0.034, hazard ratio 0.35, 95% confidence interval 0.13-0.92), whereas in females no difference was noted (p=0.82). Furthermore, donor gender also affected outcome and transplantation from female HLA-DRB1 *04 carrier donors resulted in superior survival compared with female non-carrier donors (p=0.01). Combined analyses including recipient/donor gender and HLA-DRB1 *04 showed that survival of male patients varied significantly according to donor gender and HLA-DRB1 *04 carriership (p=0.04) with best survival among HLA-DRB1 *04 carriers transplanted from female donors. Of relevance to our results, HLA-DRB1 *04 has been documented as risk allele group for lymphoid malignancies, and studies described a male-specific risk. We believe that our findings provide further supporting evidence for sex-specific alterations secondary to HLA-DRB1 *04 or related genes. Further studies are warranted to evaluate whether in contrast to general favour of male donors HLA-DRB1 *04 carrier patients with lymphoid malignancies could benefit from transplantation from female donors