ABO incompatibility as an adverse risk factor for survival after allogeneic bone marrow transplantation

BACKGROUND: Graft ABO incompatibility has not been thought to affect patient survival after allogeneic bone marrow transplantation, although it may be associated with prolonged erythroid aplasia and immediate or delayed hemolysis. STUDY DESIGN AND METHODS: A retrospective analysis of a cohort of 292 allogeneic transplant recipients measured survival in a subgroup of ABO-incompatible bone marrow graft recipients. RESULTS: Patients with acute myelogenous leukemia or myelodysplastic syndrome receiving non-T-cell-depleted bone marrow grafts had an 85-percent greater risk of death within 100 days of transplant (relative risk, 1.85, 95% CI, 1.33-2.58; p = 0.003) than comparable patients receiving ABO-compatible grafts. Both ABO major- and minor-mismatched graft recipients were at risk. The increased mortality rate was not due to an increase in graft failure or acute graft-versus-host disease; rather, patients died of multiple-organ failure and sepsis, which is consistent with regimen-related toxicity. This effect was not seen in a larger group of 112 chronic myelogenous leukemia patients undergoing similar treatment. CONCLUSION: ABO incompatibility may be a significant prognostic risk factor after allogeneic bone marrow transplantation in susceptible subgroups of recipients. Care is necessary to design hematopoietic stem and progenitor cell-processing and -transfusion policies to minimize this risk.