Phagocytic and chlamydiae-inhibiting activities of stimulated and nonstimulated periotneal mouse macrophages.

Phagocytic and chamydiacidal properties of nonstimulated and stimulated mouse mononuclear cells for two Chlamydia psittaci 6BC strains were investigated. It was determined that macrophages kept in monolayer culture (i.e. stimulated phagocytes) developed much more efficient chlamydiacidal ability than did cells kept in suspension directly after harvest (i.e. nonstimulated phagocytes). A thousandfold decrease of chlamydial infectivity was observed 60 min after induction of phagocytosis in stimulated macrophages, irrespective of the strain offered. In contrast, the infectivity of both chlamydial strains remained essentially unchanged up to 1 h after phagcoytosis by nonstimulated phagocytes. Electron-microscopic examination indicated that chlamydiae were disintegrated within phagolysosomes of stimulated phagocytes within minutes after phagocytosis, although ultrastructurally altered chlamydiae not enclosed in vacuoles were also observed in the cytoplasm of several mononuclear phagocytes at different times after phagocytosis.