Use of radioimmunoassay for the detection of circulating antistreptococcal antibody in patients with glomerulonephritis.

A method of radioimmunologic quantitation of antibodies to streptococcal antigen separated from the cell wall extract of group A type T12 strain has been developed. The highest values of radioactive antigen binding were observed in acute glomerulonephritis (75%), as compared to chronic glomerulonephritis in which values of 25% to 56% were found depending on the morphology of renal changes. It was shown that none of the patients with pyelonephritis, Alport's syndrome, lupoid nephritis and polycystic renal disease had elevated antistreptococcal antibody levels. In contrast to this, all patients with tonsillitis and proteinuria exhibited increased titre of this antibody. It was shown that the antigen is related neither to M-protein nor to group A polysaccharide and that it is not type-specific because the binding of antigen T12 may be inhibited by the antigen produced from strain T5. Although the antigen is not type-specific, some differences in the response to antigens prepared from various types of streptococci in patients with different forms of chronic glomerulonephritis are observed.