Impact Of High Resolution HLA Mismatch On Outcomes Of Unrelated Peripheral Blood Stem Cell Transplantation

Abstract

IntroductionHigh resolution HLA disparity between donor and recipient affect transplantation outcomes of unrelated peripheral blood stem cell transplantation (PBSCT), however the importance of individual loci in a high resolution level still remains unclear. The purpose of current study was to examine the impact of high resolution HLA disparity on transplantation outcome. Materials and methodsWe retrospectively analyzed 104 pairs of donor-recipient, who received PBSCT from unrelated donors (MUDs) between January 2009 and August 2012 at the Samsung Medical Center. The result of high resolution typing of HLA-A, -B, -C and -DRB1 were reviewed. Clinical outcomes were evaluated in terms of acute/chronic GVHD, relapse and survival. ResultsAll but 11 cases (89.4%) received serologically matched transplantation. Of the 104 pairs, mismatching at high resolution level was observed in 34 cases (32.7%), containing 1, 2, and 3 or more mismatches in 15 (14.4%), 14 (13.5%) and 5 (4.8%) cases. According to the HLA loci, mismatches were detected in 12 (11.5%), 10 (9.6%), 10 (9.6%) and 21 cases (20.2%) on HLA-A, -B- C, and DRB1 loci. There were no significant differences in the incidence of chronic GVHD between the 8/8 matched pairs and 7 or less/8 matched pairs. However, the incidence of grade II-IV acute GVHD was significantly higher in patients with HLA-A mismatch compared with those with full matched HLA-A (p=0.011), although it was not translated to differences in survival or relapse. Overall survival was significantly inferior in patients with mismatching on HLA-B loci (p=0.0399), and it was mainly attributable to increasing non relapse mortality (NRM) in these patients (p=0.0252). ConclusionThe potential role of high resolution HLA disparity on the development of GVHD or transplant outcomes has not been confirmed in the present study, and further study with larger number is necessary. Of note, high-resolution mismatch on HLA-B might be associated with worse outcomes in unrelated donor PBSCT. Disclosures:No relevant conflicts of interest to declare.