Further studies on the differentiation of a cell line of myeloid leukemia

Abstract A limited time of contact with a conditioned medium from embryo cells induced phagocytotic activity in a cell line of myeloid leukemia followed by the loss of colony forming and leukemogenic capacity. After two days in a high concentration of the conditioned medium, the colonies showed morphological changes which indicated the differentiation of this line of cells. The differentiation‐stimulating factor present in the conditioned medium was relatively thermolabile, while the growth‐stimulating factor was highly thermostable. Both factors could pass through a dialysis membrane.