Mast-cell products and heparin stimulate the production of mononuclear-cell factor by cultured human monocyte/macrophages.

Purified mast cells derived from rat peritoneal fluids and dog mastocytomas were extracted with 1 M-NaCl and sonication techniques. The mast-cell products increased the production of mononuclear cell factor from human peripheral blood mononuclear cells in culture, as judged by the enhanced stimulation of prostaglandin E (2-5 fold) and collagenase (3-11-fold) production by cultured adherent synovial cells. Heparin alone (1-10 micrograms/ml) induced a similar stimulation of mononuclear-cell-factor production by monocyte cultures, whereas histamine (1-10 micrograms/ml) had no effect. The stimulatory effect of mast-cell products and heparin represented a direct effect on mononuclear cells; they did not potentiate the effect of monokine on the synovial cells. These results suggest that mast-cell-macrophage interactions may play a significant role in the pathogenesis of inflammation and connective-tissue degradation.