Antibodies to N-acetylglucosamine and heparin in acute and remission phases of rheumatic fever.
The etiology of acute rheumatic fever (ARF) is believed to involve an immunological response to group A streptococcal antigens. Antibodies to group A carbohydrate (A-CHO) have been reported in ARF and rheumatic heart disease patients. As N-acetylglucosamine (GlcNAc) units form the major immunodominant regions in A-CHO antigens, we investigated levels of antibodies to GlcNAc and heparin (with repeated sequences of GlcNAC) in rheumatic fever (RF) patients. Serum samples from 26 acute cases (ARF), 18 remission cases and 17 normal healthy subjects were analyzed for IgG and IgM levels of antibodies to GlcNAc and heparin. High titres of IgG antibodies to heparin and GlcNAc were observed in the ARF group in comparison with controls (p less than 0.0025 and 0.0125 respectively). There was no difference in the levels of IgM antibodies. Remission group demonstrated low titres of IgG to heparin and GlcNAc (p less than 0.01 and 0.0125 respectively) in comparison with ARF group. Heparin antibodies of IgM class was comparatively lower in remission group (p less than 0.005). While the role of these antibodies in different phases of RF needs to be investigated, we conclude that GlcNAc antibodies do not play any role in the pathogenesis of RF or rheumatic heart disease.