Immunoglobulin isotype response to the group-A streptococcal carbohydrate in humans.

We used an ELISA to determine the levels of specific anti-GAS carbohydrate IgG, IgM and IgA in 34 patients with acute rheumatic fever (ARF) with or without carditis, in 15 patients with acute glomerulonephritis (AGN) and in 18 control patients with noncomplicated GAS pharyngitis. Patients with ARF and AGN showed a significantly higher geometric mean titer as well as a higher frequency of elevated Ig of the IgG, IgM and IgA A-CHO class antibodies during the acute stage of this disease, when compared to controls. The IgM and IgA geometric means of the antibody were higher in ARF with carditis patients as compared to the non-carditis or AGN patients; however, the differences were not significant. In addition a lower frequency of antibody decline was observed in ARF with carditis patients who were seen in follow-up after a 1-year period, supporting previous observations of the persistence of this antibody in patients with rheumatic heart disease.