Studies on the Measurement of Antibody against C-Polysaccharide Antigen of Group A Streptococcus by the Enzyme-Linked Immunosorbent Assay

Abstract

The present paper describes the measurement by ELISA of antibody against group A streptococcal specific C-polysaccharide in the immunized rabbit and human sera with trypsinpronase treated whole cells as antigen.
The optimal concentration of the enzyme-treated whole cells for coating to wells was 2×10⁷cells/well. Absorption tests with whole cells of group A streptococcus, purified C-polysaccharide and N-acetylglucosamine indicated that the antibody specific to C-polysaccharide was detected by ELISA. There was a highly significant correlation between the anti-C-polysaccharide antibody titrated with enzyme-treated whole cells and that with purified C-polysaccharide as antigen. When the antibody titers (IgG class) against the enzyme-treated whole cells of the sera of patients with acute post-streptococcal glomerulonephritis and rheumatic fever were compared with those of the sera of healthy individuals by ELISA, the former was significantly higher than the latter.
The results suggest that anti-C-polysaccharide antibody can be measured by ELISA with enzyme-treated whole cells as antigen.