Abstract
The frequency of normal granulocyte colony-forming cells in the bone marrow of Yemenite Jews with genetic, absolute neutropenia and no special tendency to infection has been studied with conditioned medium from human embryo fibroblasts. Cells from these neutropenic patients gave an average of about twice the number of granulocyte colonies as bone marrow cells from nonneutropenic patients. No morphologic abnormalities were observed in the granulocytes in bone marrow smears or in colonies formed in vitro. The results indicate that the neutropenia in these patients was not due to a deficiency of granulocyte colony-forming cells. It is suggested that the neutropenia is due to a defect in the release mechanism of mature granulocytes from the bone marrow to the peripheral blood.
