Quantitative and qualitative analysis of stem cells of patients with aplastic anaemia

3 different methods, (1) assays of CFU-Cs and CFU-Es, (2) responsiveness of CFU-Cs and CFU-Es to low doses of CSF and ESF, respectively and (3) effects of ALG on CFU-C colony formation in vitro, were used to evaluate the quantitative and qualitative defects of stem cells in 28 patients with aplastic anaemia. Some patients with aplastic anaemia who had attained complete remission several years previously, exhibited severely depressed in vitro CFU-C colony formation. This suggests that the defect persists for a long time after clinical complete remission. Residual marrow CFU-Cs and CFU-Es did not have defective responses to the humoral stimulating factors, CSF and ESF. No patient showed a rise of colony number after treatment with ALG in vitro.