Lysosomes and the "toxicity" of Rickettsiales. V. In vivo relationship of peritoneal phagocytes and egg-attenuated C. psittaci 6BC

Abstract

The investigations reported here follow the lines of our earlier studies and represent an attempt to identify the inhibitory activities of the lysosomes of mononuclear and polymorphonuclear phagocytes (PMN's) in the peritoneal cavity of mice after intraperitoneal infection with an egg-attenuated C. psittaci 6BC strain (avirulent for mice). Presumptive evidence indicates that lysosomes of macrophages are refractory to "nontoxic" chlamydial particles that are initially ingested, while the adsorption to, and (or) uptake of, these agents by PMN's is followed by disintegration of PMN's which causes release of lytic substances from them. Macrophages infected in vivo are nonspecifically "activated" and some of them "transform" after maintenance in vitro into large epitheloid cells containing numerous well-demarcated chlamydial inclusions in the cytoplasm. Except for the inclusions neither damage nor lysosomal acid phosphatase release was detected in these cells. The Chlamydiae-induced inflammatory reaction and the possible persistence of "nontoxic" Chlamydiae in chronic infection are discussed.