Production of growth factor activity for fibroblasts by human monocyte-derived macrophages.

Macrophages, derived from human monocytes by in vitro culture, released a growth factor for rabbit lung fibroblasts. The release of growth factor was increased following stimulation with both soluble (lipopolysaccharide and phorbol myristate acetate) and particulate (opsonized zymosan) substances. Production of the growth factor activity was dependent on the length of time the monocytes were in culture, the presence of serum during the period of monocyte maturation, and macrophage protein synthesis. The inability of serum-deprived monocytes to produce growth factor could be reversed by adding back serum. Eicosatetraynoic acid and dexamethasone but not indomethacin inhibited the production of growth factor suggesting that arachidonic acid metabolites other than prostaglandins may regulate growth factor production.