3-OR: DONOR SELECTION FOR HUMAN CELL TRANSPLANTATION AND THE ROLE PLAYED BY ANTI-DP ANTIBODIES

Aim Current Hematopoeitic cell transplant (HCT) donor selection strategies do not include matching at the DP locus and this locus is rarely typed for in either the related or the unrelated potential donor setting. Since the advent of the solid phase assays for detection of anti-HLA antibodies, our ability to successfully detect and determine specificity of both Class I and II antibodies has been greatly improved, particularly following the introduction of the single antigen bead platforms. We report on 3 HCT candidates who developed strong antibodies to DP (DPA/B subunits) which were found to profoundly affect the donor selection process and hence the possibility for transplant. Methods Single Antigen HLA antibody screening was performed using One Lambda LABScreen Single Antigen kits. Results were evaluated for the presence of DP antibodies. DPA/B typing was performed using either One Lambda LabType SSO kits and/or Micro SSP trays. Results At our center, all candidates for HCT are screened for the presence of anti-HLA antibodies. Antibody screening results become particularly important and are used to guide donor selection in instances where patients, due to the unavailability of matched related donors or URD are restricted to mismatched, haplotype matched or cord blood donors. We report the case of 3 patients who developed strong antibodies to both the DPA1 and DPB1 subunits of DP. The strength of reactivity of the DP single antigen beads ranged from 1K- > 15K MFI and resulted in positive B-cell CDC and Flow crossmatches with appropriately MM DP donors. Conclusions Finding appropriate HCT donors, lacking the offending DPA/B antigens impacts the HCT donor search process significantly. 1 patient, with rarer HLA types was unable to proceed to transplant with a URD for 2.5 years. These 3 cases highlight the influence that the presence of DP antibodies can have on the donor selection process and on the possibility of transplant. Pereira: Linkage Biosciences: Consultant; Science Med Advisor; Stockholder; Scisco Genetics: Consultant; Science Med Advisor.