Detection of antibodies in human sera to streptococcal groups A and C carbohydrates by a radioimmunoassay.
Human antibodies to streptococcal groups A and C carbohydrates were measured quantitatively with a radioimmunoassay using tyrosylated  125I carbohydrate. Analysis of acute and convalescent sera from people with groups A or C streptococcal pharyngeal infection or persistent carriage revealed a significant rise in antibodies. Inhibition reactions with the cold carbohydrate indicated the specificity of the elicited antibodies. In some instances, group C as well as group A antibodies occurred after group A pharyngeal infections. Further clinical and epidemiological studies are required to determine the significance of group-specific antibodies. Antistreptolysin-O (ASO) rises were observed in individuals with group C antibody responses after persistent group C pharyngeal carriage. For this reason, epidemiological surveys that rely primarily on ASO surveys to determine the incidence of group A streptococcal infections must be interpreted with caution, at least in the developing countries, where group C pharyngeal carriage is common.
D000907:Antibodies, Bacterial / Q000032:analysis; D001666:Binding Sites, Antibody; D002241:Carbohydrates / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007457:Iodine Radioisotopes; D010612:Pharyngitis / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods*; D013290:Streptococcal Infections / Q000276:immunology; D013291:Streptococcus / Q000276:immunology*; D013297:Streptococcus pyogenes / Q000276:immunology*
D000907:Antibodies, Bacterial; D002241:Carbohydrates; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007457:Iodine Radioisotopes