The effect of recombinant cytokines on the proliferative potential and phenotype of cells of the human myelomonocytic leukaemia line, RC-2A

Cells of the human myelomonocytic line RC-2A can be induced to differentiate towards mature monocytes by culture in the presence of phytohaemagglutinin-treated lymphocyte conditioned medium (Lyons and Ashman, Leukemia Res. 11, 797, 1987). We have now examined the effect on RC-2A cells of some (recombinant) cytokines which might be present in conditioned medium. Gamma interferon most closely mimicked the effect of conditioned medium in inducing clonogenic suppression and the induction of monocytic maturation over 7 days of culture. Granulocyte colony stimulating factor induced enhancement of proliferation followed by clonogenic suppression, while granulocyte-macrophage colony stimulating factor had a purely stimulatory effect on proliferation over a 7-day period. Tumour necrosis factor alpha failed to affect cell proliferation or to induce characteristic monocytic differentiation, but did increase the expression of C3bi receptors. We conclude that RC-2A cells have receptors for all four cytokines studied, and that gamma interferon is a major differentiation-inducing stimulus for these cells.