ENHANCEMENT OF MACROPHAGE-COLONY-STIMULATING FACTOR-INDUCED GROWTH AND DIFFERENTIATION OF HUMAN MONOCYTES BY INTERLEUKIN-10

Interleukin-10 (IL-10) has been reported to be a negative cytokine for monocytes/macrophages. In the present study, we showed that IL-10 is rather a positive cytokine and augments the growth and differentiation of human monocytes stimulated with macrophage colony-stimulating fact or (M-CSF). Highly purified adherent human monocytes were cultured for 7 days with M-CSF in the presence or absence of IL-10. The number of recovered cells increased in the culture of monocytes with M-CSF + IL- 10 compared to the culture with M-CSF alone. IL-10 alone was not enoug h to maintain the survival and differentiation of monocytes into macro phages. Morphological change cultured in M-CSF was also accelerated by addition of IL-10, and macrophages cultured in M-CSF + IL-10 were mor e elongated compared to macrophages cultured with M-CSF alone. Binding of I-125-M-CSF to monocytes incubated with M-CSF + IL-10 was about 1. 7-fold higher than that to monocytes incubated with M-CSF alone. In ac cordance with the binding study, Northern blot analysis showed that th e levels of the expression of c-fms, M-CSF receptor, mRNA in macrophag es cultured in M-CSF + IL-10 were higher than that in macrophages cult ured in M-CSF alone. Macrophages cultured in M-CSF + IL-10 expressed h igher level of Fc gamma RI, II, III, and showed augmented Fc gamma rec eptor mediated phagocytosis. The former also produced higher level of H2(O)2 and O-2(-), when stimulated with zymosan, and of IL-6 when stim ulated with lipopolysaccharide compared to the latter. These results t aken together suggest that IL-10 augments the growth and differentiati on of human monocytes cultured in M-CSF. (C) 1997 by The American Soci ety of Hematology.