Effect of human recombinant granulocyte-macrophage colony-stimulating factor and IL-3 on the expression of surface markers of human monocyte- derived macrophages in long-term cultures

Granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-3, which are involved in the maturation of cell precursors in the bone marrow into granulocytes and macrophages, were found also in chronic inflammatory sites, and their production might be enhanced by inflammatory stimulants. These findings led us to examine the effect of human recombinant GM-CSF (hrGM-CSF) and hrIL-3 on the maturation of human peripheral blood monocytes in long- term tissue cultures and on the expression of functional membrane bound molecules. Adherent human peripheral blood monocytes cultured for 2 weeks in the presence of GM-CSF or IL-3 were examined for viability and adherence, expression of membranal HLA-DR, CD-14, and IL-1α, and LPS triggered TNF-α production. GM-CSF and IL-3 treatment increased the viability of adherent cells after 2 weeks in culture, and elevated the expression of membranal HLA- DR, CD-14 (LPS receptor), and IL-1α. Such treated macrophage cultures also showed elevated production of TNF-α. The results indicate that GM-CSF and IL-3 facilitate the long-term maturation of monocytes into macrophages, augment their capacity to bind LPS, and elevate the release of cytokines involved in inflammatory and granulomatous reactions.