The effect of the leukemic cell line HL60 and acute myeloblastic leukemic cells before and after induction of differentiation on normal pluripotent hematopoietic progenitors (CFU-GEMM).

A leukemic cell line (HL60) and acute myeloblastic leukemia (AML) cells from six patients were co-cultured with normal marrow cells to assess their effects on growth of normal CFU-GEMM. The effects of the following inducers: 12-0-tetradecanoyl-phorbol-13-acetate (TPA), retinoic acid (RA), dimethylsulphoxide (DMSO), 1-25 (OH) D3 (Vitamin D3) and PHA-LCM on both the HL60 and AML cells, were studied. Inhibition of growth of normal CFU-GEMM was observed in the co-cultures in the presence of 1 X 10(4) HL60 or AML leukemic cells/ml. This inhibition was reversed by pretreating the HL60 line with vitamin D3, TPA and RA. No effect on growth of CFU-GEMM was noted when DMSO and PHA-LCM were used. AML cells were morphologically induced to differentiate by TPA or RA in all six cases. In three cases, reversal of inhibition of growth of normal pluripotent hemopoietic progenitors occurred and in three the inhibition of growth persisted. Regulation of inhibition by different inducers did not seem to correlate in all cases with morphological differentiation.