title: Serologic cross-reactions among streptococcal group A, A-variant, and C polysaccharides.
abstract: Serologic cross-reactions among streptococcal groups A, A-variant (A-V), and C cell wall polysaccharides were found previously in studies employing capillary or quantitative precipitin techniques. Similar cross-reactions occur with radioimmune precipitation using extrinsically labeled 125I-streptococcal antigens. This study was performed to determine the degree of cross-reactivity when intrinsically labeled 14C-polysaccharide antigens were used in the radioimmune precipitin assay. Unadsorbed antisera from rabbits immunized with group A streptococci bound 3-5% as much 14C-A-V antigen as homologous A carbohydrate but undetectable amounts of C polysaccharide. Similarly, A-V antisera bound 3-5% as much 14C-A or 14C-C carbohydrate as A-V antigen. Group C antiserum bound 1-2% as much A and A-V antigens as C carbohydrate. Thus, less than 3% of intrinsically labelled 14C-A or 14C-C carbohydrate represents exposed A-V antigenic sites, i.e., exposed polyrhamnose backbone. Otherwise, group A, C, or A-V carbohydrates failed to exhibit heterologous determinants. Anti-peptidoglycan antibodies in antisera did not result in serologic cross-reactivity. These data suggest that formamide-extracted streptococcal group-specific polysaccharides, intrinsically labeled with 14C, may possess greater group specificity than 125I-carbohydrates and yield only negligible cross-reactivity with heterologous antisera. This degree of cross-reactivity does not appear to be sufficient to account for the persistently elevated serum levels of antibody to group A carbohydrate in patients with rheumatic heart disease.
mesh_terms: D000116:Acetylgalactosamine / Q000494:pharmacology; D000117:Acetylglucosamine / Q000494:pharmacology; D000118:Acetylglucosaminidase / Q000494:pharmacology; D000818:Animals; D000907:Antibodies, Bacterial / Q000502:physiology*; D000942:Antigens, Bacterial / Q000276:immunology*; D001667:Binding, Competitive; D003429:Cross Reactions; D014644:Genetic Variation; D007106:Immune Sera / Q000235:genetics / Q000494:pharmacology; D010457:Peptidoglycan / Q000494:pharmacology; D011135:Polysaccharides, Bacterial / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011817:Rabbits; D012210:Rhamnose / Q000494:pharmacology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007106:Immune Sera; D010457:Peptidoglycan; D011135:Polysaccharides, Bacterial; C027158:polysaccharide C-substance (Streptococcus); C036112:streptococcal polysaccharide group A; D000118:Acetylglucosaminidase; D000116:Acetylgalactosamine; D012210:Rhamnose; D000117:Acetylglucosamine