Myeloid differentiation-inducing factors produced by pokeweed mitogen-treated normal G1/0 lymphocytes but not chronic lymphocytic leukemia cells.

HL-60 human promyelocytic leukemia cells undergo myeloid differentiation and G1/0 specific growth arrest in response to an activity produced by pokeweed mitogen stimulated peripheral blood mononuclear cells. Elaboration of this myeloid differentiation inducing activity does not require lymphocytic proliferation or pokeweed mitogen induced B-lymphocyte differentiation. The activity is a product of initially stimulated G1/0 lymphocytes. It is not produced by proliferating lymphocytes. The activity is not elaborated by G1/0 peripheral blood lymphocytes of patients with chronic lymphocytic leukemia, cells which are proliferatively refractory to pokeweed mitogen stimulation.