The Chemical Compositions of the Cell Wall of Salmonella typhimurium Affecting the Clearance-Rate in Mouse; Influence of Specific Antibody

Abstract

The opsonic effect of specific antibodies against Salmonella typhimurium wild-type LT2 strain and its mutant strains possessing various cell wall polysaccharides was examined as to the in vivo clearance of the bacteria from the blood or peritoneal cavity of mice and also the in vitro phagocytic process of the bacteria by mouse peritoneal macrophages. Clearance-rate of the strains, which possessed a repeating polymer of O side chain (tetrasaccharide sequence of abequosyl-mannosyl-rhamnosyl-galactose) or one unit of the tetrasaccharide (rfc mutant strain) in their cell wall, was greatly enhanced by the administration of specific antiserum to mice prior to infection. The opsonic effect of the specific antiserum to these strains is undoubtedly attributed to the antibody directed to the O side chain polysaccharide, while in the clearance of the rfc mutant strain the antibody to R-core polysaccharide also was effective. The mutant strains, which lack the O side chain in their cell wall, were cleared so easily that the opsonic effect of the antisera could not be assessed. The study of in vitro phagocytosis of ³²P-labeled organisms by macrophages also demonstrated a close correlation between the opsonic activity of the specific anitserum and the cell wall polysaccharide constitution of the organisms. Furthermore, it was found that rough mutants are more easily fragmented within phagocytic cells than the wild-type strain cells.