In order to perform a reasonable chemotherapy to patients with acute leukemia, drug sensitivity test on leukemic stem cells is considered to be valuable. We tried to form leukemic colony from peripheral blood cells of 22 patients with acute non-lymphocytic leukemia by the method described by M.D. Minden et al and performed drug sensitivity test on leukemic stem cells from 5 patients. According to the colony forming ability and the characteristics of the cells in colony, 22 patients were classified into three groups, which were Group I (no colony formation), 8 cases, Group II (T-cell colony formation), 5 cases and Group III (leukemic colony formation), 9 cases. The number of colonies obtained from Group III is 30-843/2×105 cells depleted of T-cells. Cells in colony had the different characteristics from one patient to another, which were immature granulocytes, macrophage like cells, and blastoid cells. Although there was detected only one type of colonies within a patient, differing from colonies from normal peripheral blood. Drug sensitivity test on leukemic stem cells to daunorubicin and cytosine arabinoside revealed that the sensitivity of leukemic stem cells was similar to that of granulocytic progenitor cells from nomal bone marrow but higher than that of T-cell progenitor cells from Group II.
