Occurrence and specificity of antibodies against group-specific polysaccharides in beta-hemolytic streptococcal infections.

We studied the possibility of detecting beta-hemolytic streptococcal infections by determining antibodies against the group specific polysaccharides from streptococci of groups A, A-variant, C and G. The methods used were radio-immunoassay with these four polysaccharides and hemagglutination of group A polysaccharide sensitized erythrocytes. Significant increases in these antibodies were rare in tonsillitis patients, whereas high concentrations of antibodies could often be observed in association with severe systemic infections or rheumatic fever. Both strictly immunogen-restricted and crossreactive antibodies could be demonstrated by isoelectric focusing and inhibition of antigen-binding. Although previously considered nonexistent, group specific carbohydrate antibodies of IgM class could also be demonstrated.