ANTI-HLA DONOR-SPECIFIC ANTIBODIES ARE ASSOCIATED TO INFECTION AND NOT TO THE ENGRAFTMENT RATE IN OUTPATIENT HAPLOIDENTICAL HEMATOPOIETIC CELL TRANSPLANTATION

Background: Recipients of a related haploidentical stem cell transplant (haplo-SCT) can have preformed antibodies to HLA donor's antigens. Objective: The aim of the study was to evaluate the engraftment rate and major clinical associations of anti-HLA donor-specific antibodies (DSA) at two mean fluorescence intensity (MFI) thresholds in recipients of an outpatient haplo-SCT. Methods: Seventy haplo-HCT recipients were analyzed. A virtual crossmatch was performed using the donor HLA typing and the recipient's anti-HLA DSA test results. Data for anti-HLA-A,-B,-C, and-DR were analyzed. Recipients with DSA >= 500 MFI were considered positive, and those with < 500 were considered negative; the same was adopted for MFI >= 1000. Results: Post-transplant infection was higher in recipients with DSA >= 500 MFI (84.6%, p = 0.041). First-year mortality was higher in DSA-positive patients >= 500 MFI, p = 0.004, and DSA >= 1000 MFI, p = 0.022, than in DSA-negative recipients. Graft failure in the first 100 days was not associated with DSA >= 500 or >= 1000 MFI. There was no difference in acute (a-GVHD) or chronic (c-GVHD) graft versus host disease between DSA-positive and negative patients. Conclusions: There was no association of anti-HLA DSA at MFI >= 500 and >= 1000 with graft failure, however, increased infection and 1st-year mortality were documented in related haplo-HCT at the MFI cutoffs studied. (REV INVEST CLIN. 2023;75(5):249-58)