FETAL ERYTHROPOIESIS FOLLOWING BONE-MARROW TRANSPLANTATION

Abstract

Fetal erythrocytes are present in older children and certain adults with hematologic disorders. To determine if regenerating bone marrow produces such cells, the blood of 7 allogeneic bone marrow transplant recipients were examined. Six patients were engrafted with donor cells, while 1 patient recovered autologous bone marrow after rejection of a marrow transplant. All 7 patients had fetal Hb levels of up to 10% by 100 days after transplant. In 3 patients, the G.gamma. to A.gamma. ratio in the fetal Hb was newborn, while in 1 it was adult. .gamma. Chain synthesis in blood and bone marrow never exceeded 20% of total non-.alpha. globin synthesis. The fetal Hb was heterogeneously distributed in the cells. High titer i antigen also appeared. All fetal characteristics declined by 200 days. Erythropoiesis during bone marrow recovery appears to be associated with an accelerated, albeit partial, recapitulation of ontogeny.