Specificity of persistence of antibody to the streptococcal group A carbohydrate in rheumatic valvular heart disease.

The specificity of the persistence of antibody to the streptococcal group A carbohydrate for mitral valve disease induced by rheumatic fever was examined. Levels of the antibody were determined in serum samples of 30 patients with rheumatic mitral insufficiency, 30 patients with mitral valve prolapse, and an equal number of normal individuals and patients with congenital heart disease. Antistreptolysin titers and anti-deoxyribonuclease B titers were also assayed in all sera. There were no differences in the incidence of elevated antibody titers or in the geometric means of the antibody titers for the normal individuals, the patients with congenital heart disease, and the patients with mitral valve prolapse. In contrast, the frequency of elevated anti-streptococcal group A carbohydrate titers and the geometric means of these titers were significantly higher in the patients with rheumatic mitral valve disease than in patients with mitral valve prolapse. This confirms the specificity of the persistent elevation of anti-streptococcal group A carbohydrate to patients with mitral valve disease induced by rheumatic fever and also suggests that the persistence of this antibody in patients with rheumatic valvular disease is not a result of a functional abnormality of the mitral valve.