Induction of Tac antigen and proliferation of myeloid leukemic cells by ATL-derived factor: comparison with other agents that promote differentiation of human myeloid or monocytic leukemic cells

We studied seven cases of myeloid leukemia at various differentiation stages to investigate the response of leukemic cells to phorbol 12- myristate 13-acetate (PMA) and various biological factors. gamma- Interferon (gamma-IFN)-treated cells expressed higher amounts of Fc receptors on leukemic cells in five out of seven cases. Expression of HLA-DR antigen of gamma-IFN-treated leukemic cells was significantly enhanced in three cases. PMA did not induce Fc receptors or HLA-DR antigen on these cells. Induction of Tac antigen, a putative interleukin 2 (IL 2) receptor, was observed in two cases after cultivation with PMA or with a novel lymphokine, adult T cell leukemia- derived factor (ADF). Cells from one of these patients expressed Tac antigen immediately after cell separation, and expression of Tac antigen was augmented by PMA and ADF. Interleukin 1 (IL 1) or IL 2 did not induce Tac antigen. Leukemic cells from this patient also proliferated vigorously in the presence of ADF but not PMA, IL 1, or IL 2.