Antibodies to a streptococcal cell wall adjuvant structure persist in patient with chronic rheumatic heart disease

Sera from 50 patients with chronic rheumatic heart disease were analysed by an enzyme linked immunosorbent assay for the presence of antibodies to the streptococcal minimal adjuvant moiety, muramyl dipeptide (MDP). The T-cell responsiveness to this structure was also studied in vitro, using the lymphocyte transformation test. Fifty four percent of the patients possessed anti-MDP antibodies in their sera when examined 5 to 25 years after the initial rheumatic attack. Such antibodies were found only in 5 to 6% of sera from healthy controls or from patients with cardiac disease of non-rheumatic origin. There was neither antigenic nor mitogenic stimulation by MDP of the T-cells from peripheral blood of chronic rheumatic heart disease patients or controls. The results point to a lifetime persistence of anti-MDP antibodies in rheumatic fever and rheumatic heart disease. Possible mechanisms by which detectable levels of such antibodies are maintained in rheumatic heart disease are discussed.