Study of differentiation of fresh human leukemic cells by low dose cytosine arabinoside (LD Ara-C) and 12-O-tetradecanoylphorbol-13-acetate (TPA).

The effect of LD Ara-C (10(-8) mol/l) (Ara-C), TPA (1.6 x 10(-7) mol/l) and 13-cis-retinoic acid (RA) (10(-6) mol/l) on the differentiation in liquid culture of bone marrow cells from 5 patients with acute lymphoblastic, 17 patients with acute myelogenous leukemia, 1 patient in myeloid and 1 in lymphoid crisis of chronic granulocytic leukemia was studied. Ara-C induced morphological and cytochemical differentiation into monocytic cells in 2 cases (M1, M5 type). TPA induced convincing morphological and cytochemical features of maturation into monocytic cells in 4 cases (two M1, one M2, and one M5 type) and into differentiated myeloid cells in 2 cases (M1, M4 type). RA in one case (M2 type) out of three AML studied induced cytochemical and immunocytochemical features of maturation. The results of the study indicate that although TPA is a better inducer of blast cell differentiation than Ara-C, however, neither is a potent differentiation agent of leukemic blasts in liquid culture. The heterogeneity of leukemic blasts within the same type of leukemia was confirmed by their different response to differentiating agents.