Abnormalities of hematopoietic progenitor cells in patients with aplastic anemia after hematologic recovery.

Hematopoietic progenitor cells were studied in 11 patients with aplastic anemia who had hematologic recovery after androgen therapy. The mean numbers of colonies derived from erythroid and granulocyte-macrophage progenitor cells (BFU-E and CFU-GM) were markedly decreased compared to normal controls. Cell-mediated suppression of colony growth as detected by coculture studies was observed in 5 patients; 4 patients for CFU-GM and one for both CFU-GM and BFU-E. It is thus concluded that the pool of hematopoietic stem cells in patients after hematologic recovery is still not fully reconstituted. In addition, this impaired reconstitution appears due in some cases to cell mediated suppression of progenitor colony growth.