DETECTION OF ANTIBODIES IN HUMAN SERA TO STREPTOCOCCAL GROUP-A AND GROUP-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 wilh caution, at least in the developing countries, where group C pharyngeal carriage is common. Copyright © 1979, Wiley Blackwell. All rights reserved