Studies on Attachment and Ingestion Phases of Phagocytosis of Mycoplasma pulmonis by Mouse Peritoneal Macrophages 1

Abstract

Summary

Studies have been made on factors which influence attachment of Mycoplasma pulmonis to the surface of mouse macrophages in vitro, and on factors which determine whether or not the attached microorganisms are ingested.

Attachment of mycoplasmas exhibited few specific requirements. Attachment occurred in media containing no broth, serum, or divalent cations, and it was not blocked by proteolytic enzymes, neuraminidase, lysozyme or by exposure of the mycoplasmas to glutaraldehyde, to heat, or to repeated freezing and thawing. Only glutaraldehyde fixation of both the macrophages and the mycoplasmas, or use of a nonionic sucrose medium prevented attachment.

In enriched tissue culture medium, the attached mycoplasmas resisted ingestion by the macrophages. This resistance was lost if the mycoplasmas were damaged or killed in various ways. Mycoplasmas treated with proteolytic enzymes under conditions not lethal for the organisms became susceptible to ingestion by macrophages, suggesting the presence of an antiphagocytic surface protein. Mycoplasmas were also rendered susceptible to ingestion on exposure to nonlethal concentrations of antimycoplasma IgG antibody; F(ab′)₂ fragments did not promote engulfment, suggesting that the F_e portion of the antibody molecule was important in the ingestion process, probably by reacting with F_c receptor sites on the macrophage.