HLA-DPB1 may play an integral role in clinical outcomes following haematopoietic stem cell transplant (HSCT), although the significance of this remains uncertain.
We retrospectively analysed the impact of HLA-DPB1 on the outcome of 200 patients that underwent primary allogeneic HSCT within our single centre, all of whom were otherwise 10/10 matched at HLA-A, -B, -C, -DRB1 and -DQB1. The number of HLA-DPB1 mismatches were assessed for each recipient-donor pair and subsequently any that were mismatched classified as either permissive or non-permissive according to the revised T-cell epitope matching algorithm (TCE-FD). For any non-permissive mismatched pairs, the vector of mismatch was also considered. The incidence of grade I-II acute graft-versus-host disease (aGvHD) was significantly influenced by HLA-DPB1 mismatching, although this did not reach significance in grade III-IV aGvHD. Those pairs with non-permissive mismatches in the GvH direction correlated with the highest risk of grades I-II aGvHD compared to those that were HLA-DPB1 matched (OR 8.93, 95% CI 2.52–31.62, p = .001).
This significance was also confirmed in multivariate analysis (OR 9.52, 95% CI 2.62–34.63, p = .001). Although no impact was observed in chronic GvHD, relapse or transplant-related mortality, those that were HLA-DPB1 matched showed a trend towards better overall survival. Our data helps to understand the role of HLA-DPB1 matching within our single centre and supports the importance of incorporating this locus as a determinant in unrelated HSCT. These findings will help to guide our local donor selection strategy in order to optimise transplant outcomes.