Multiplication of human fetal myelomonocytic precursors in medium conditioned by acute myelocytic leukemia cells treated by 12-O-tetradecanoyl phorbol 13-acetate (TPA).

An 8-21 fold multiplication of myeloid cells and macrophages was observed in tissue culture from human fetal bone marrow. Proliferation of the cells was triggered by medium conditioned by acute myelocytic leukemic cells exposed to 12-O-tetradecanoyl phorbol 13-acetate (TPA). The medium was designated as TPA-treated cell conditioned medium (TPACCM).