Biological properties of a granuloma glycoprotein that inhibits macrophage phagocytosis.

The biological activity of a purified glycoprotein inhibitor isolated from mature (42-day) polyvinyl sponge granulomas on macrophage phagocytosis was examined under a variety of in vitro conditions. Its activity was compared with partially purified inhibitor isolated from young (14-day) sponge granulomas. Experiments were conducted to define the mechanism of action of the inhibitor protein, and to differentiate it from other substances known to affect macrophage function. Inhibitor activity was demonstrated in neutral salt-soluble extracts from open wound granulation tissue, guinea pig and NZB/NZW mouse spleen, and acute-phase guinea pig serum. Fresh guinea pig serum and extracts of normal guinea pig tissues did not contain inhibitor material. Immunofluorescent studies demonstrated that the inhibitor was localized in or on a subpopulation of mononuclear cells within the sponge granuloma.