Regeneration of erythropoiesis after related- and unrelated-donor BMT or peripheral blood HPC transplantation: a major ABO mismatch means problems

BACKGROUND: Blood group incompatibility in allogeneic BMT is common but doe s not appear to affect the outcome in terms of incidence of graft rejection or delayed engraftment. However, major ABO incompatibility may be associat ed with prolonged erythroid aplasia. STUDY DESIGN AND METHODS: In a retrospective analysis of 286 allogeneic tra nsplant recipients, the prevalence of prolonged erythroid aplasia, includin g pure RBC aplasia, was determined. RESULTS: Patients receiving major ABO-incompatible grafts showed a signific ant delay in reticulocyte engraftment (median, 32 days; range, 12-347) from that in patients receiving ABO-identical (20; 10-152) or minor ABO-incompa tible (21;12-47) grafts. Pure RBC aplasia occurred in 7 (3%) of 240 evaluab le recipients and was observed only in the major ABO-incompatible group (7/ 43, 16%). Treatment of pure RBC aplasia consisted of either plasma exchange , which resulted in a response within 16 to 68 days, or immunoadsorption, i n which the response occurred between Days 119 and 204 after initiation of treatment. CONCLUSION: Major ABO incompatibility may lead to delayed reticulocyte engr aftment, resulting in prolonged transfusion dependency and increased risks of transmission of infection and iron overload. Therefore, therapeutic stra tegies should be taken into consideration to allow erythroid reconstitution in these patients.