Opposing effects of 12-O-tetradecanoylphorbol 13-acetate on human myeloid and lymphoid cell proliferation.

The effect of 12-O-tetradecanoylphorbol 13-acetate (TPA) on human hematopoietic cells has been investigated. It was found that 1-10 ng/ml of TPA totally abrogated erythroid and granulocytic colony growth and, simultaneously in the presence of PHA, stimulated T-lymphocyte colony formation. TPA concentrations insufficient to inhibit myeloid colony growth also failed to stimulate lymphocyte colony formation. Optimal culture conditions for the growth of these colonies required the presence of TPA, PHA, and leukocyte-conditioned medium in the cultures. Cells within the colonies were 80-90% E-rosette positive and by monoclonal antibody characterization contained 45-66% OKT3-positive cells. Colony-forming cells were found in both E-rosette-positive and-negative fractions. Although by cell surface marker characterization the cells within the colonies had properties of T-cells, the exact relationship of cells forming colonies under these conditions to those detected in other T-cell colony assays remain to be determined.