Polysaccharides serological cross-reactions

Natural Immunity, and Polysaccharide Serological Cross-reactions...200... 

By 1945, Stacey speculated about the possibility of a structural relationship between Pneumococcus capsular polysaccharides and those produced by other organisms. With Miss Schliichterer, he had examined the capsular polysaccharide of Rhizobium radicicolum. This polysaccharide gave a precipitin reaction in high dilution, not only with Type III Pneumococcus antiserum, but also mixed with antisera from other Pneumococcus types. The chemical evidence indicated that the polysaccharide resembled the specific polysaccharides of Types I and II Pneumococcus. A decade later, the acidic capsular polysaccharide from Azoto-bacter chroococcum, a soil organism, was studied. It, too, produced serological cross-reactions with certain pneumococcal specific antisera. Although the molecular structure of the polysaccharide was not established, adequate evidence was accumulated to show a structural relationship to Type III Pneumococcus-specific polysaccharide. This was sufficiently close to account for the Type III serological cross-relationship. 

K62 (23), have been elucidated, mostly using a combination of methylation analysis. Smith degradation, partial hydrolysis with acid, and H n.m.r. spectroscopy. In some cases e.g. Klebsiella serotypes K13, K25, and K37), depolymerization of the polysaccharides was accomplished by glycanase activities associated with particles of Klebsiella bacteriophages. Serological cross-reactions also revealed similarities in the structures of certain capsular polysaccharides for example, the polysaccharide from Klebsiella serotype K13 (18) cross-reacted with that from Klebsiella serotype K2, which has an identical structure except for the absence of the terminal 3,4-0-(l-carboxyethylidene)-P-D-galactopyranosyl residue. 

On the basis of the n.m.r. spectra, various structural assignments have been made to polysaccharides of S. schenkii, including a neutral mono-L-rhamnosyl-D-mannan and an acidic L-rhamno-D-mannan. Many strains from species of Sporothrix, Ceratocystis, Europhium, and Graphium have exhibited serological cross-reactions with S. schenckii, and contain polysaccharides composed of residues of L-rhamnose and D-mannose. The d-galacto-D-mannan of Schizosaccharomyces pombe has been located at the periphery of the cell wall and near the plasmalemma. No evidence was obtained for the presence of chitin. 

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