Granulocytic progenitor cells in aplastic anaemia.

The characteristics and the concentration of granulopoietic colony forming cells (CFC) were examined in 22 patients with aplastic anaemia at different stages of their disease. Additionally the ability of the patients' peripheral leucocytes to elaborate factors necessary for colony stimulation in vitro (CSA) was studied. The ability of the patients' cells to generate CSA was shown to be unaffected. However, the incidence of CFC within the marrow and peripheral blood suspensions was significanlty reduced in all patients. The results suggest a reduced compartment size of CFC even in those patients who have recovered from aplastic anaemia. This may indicate that the disturbances in the preceding compartments of the haemopoietic cell renewal system still persist after recovery from the acute bone marrow failure.