EFFECT OF HUMAN RECOMBINANT GRANULOCYTE-MACROPHAGE COLONY-STIMULATINGFACTOR 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, w hich are involved in the maturation of cell precursors in the bone mar row into granulocytes and macrophages, were found also in chronic infl ammatory sites, and their production might be enhanced by inflammatory stimulants. These findings led us to examine the effect of human reco mbinant GM-CSF (hrGM-CSF) and hrIL-3 on the maturation of human periph eral blood monocytes in long-term tissue cultures and on the expressio n of functional membrane bound molecules. Adherent human peripheral bl ood monocytes cultured for 2 weeks in the presence of GM-CSF or IL-3 w ere examined for viability and adherence, expression of membranal HLA- DR, CD-14, and IL-1 alpha, and LPS triggered TNF-alpha 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-1 alpha. Such treated macrophage cultures also showed elevated production of TNF-alpha. The results indicate th at GM-CSF and IL-3 facilitate the long-term maturation of monocytes in to macrophages, augment their capacity to bind LPS, and elevate the re lease of cytokines involved in inflammatory and granulomatous reaction s.