Erythropoietic function following major ABO-incompatible SCT.

Erythropoietic function following major ABO-incompatible SCT was related to the disappearance of clinically significant host antidonor isohemagglutinins and was further affected after NST by the relationship between the occurrence of this parameter and the time of conversion to full donor (loss of recipient) myeloid chimerism. ▪, host antidonor isohemagglutinin above 1+; ▨ detectable donor RBC chimerism; and ▥, detectable host myeloid chimerism. (A) Reticulocyte counts recovered more slowly after myeloablative SCT (n = 12) compared with NST (n = 14). Reticulocyte counts after NST decreased significantly at the time of conversion to full donor myeloid chimerism, reflecting loss of autologous erythropoiesis at a time when persistent host antidonor isohemagglutinin activity inhibited the onset of donor RBC chimerism. Error bars (± SEM) are shown at points with significant differences between NST and myeloablative SCT (P < .05). Laboratory analysis for the degree of host myeloid chimerism after myeloablative SCT was not performed. (B) Data for patients following NST who had either early donor RBC chimerism, late donor RBC chimerism with PRCA, or late donor RBC chimerism without PRCA. In patients with delayed donor RBC chimerism, full donor myeloid chimerism occurred significantly sooner in those with PRCA compared with those without PRCA. The time intervals between conversion to full donor myeloid chimerism and a decrease in host antidonor isohemagglutinins to 1+ or lower were significantly different among these 3 groups.