A macrophage differentiating factor derived from human T cell line HUT102 acting on a mouse myeloid cell line M1.

Human T cell leukemia virus type I-transformed T cell line HUT102 constitutively secreted soluble factors which induced differentiation of a murine myeloid leukemic cell line, M1, to increase the immune complex-binding and/or phagocytizing capacity. This macrophage differentiating factor(s) (MDF) was purified from the culture supernatants of HUT102 cells by using several steps of column chromatography and novel immune-adherence and/or immune-phagocytic assays. The finally purified MDF activity was detected in the fraction that consisted of 40,000- and 45,000- molecular weight molecules. Antibodies specific for human interleukin-6 or for human granulocyte-colony stimulating factor, both of which have differentiation-inducing activity on M1 cells when used as a single factor, could not neutralize the MDF activity. These findings suggest that the 40,000- and/or 45,000- molecular weight molecules in the HUT102 cell products may be possible novel differentiation-inducing factors acting on a murine macrophage lineage across the species barrier.