What is the mechanism of acute rheumatic fever

Cross reactivity with endogenous antigen Acute Rheumatic fever results from immune response to group A streptococci. - The main factor responsible for virulence in infection with streptococcal A group is "M" protein. - The body mounts an immune response against streptococci A organism by producing antibodies directed against the "M" protein. Antibodies directed against the "M" protein of streptococci have been shown to cross react with self antigens in the hea. - The streptococcal M protein and the human myocardium appears to be identical antigenically. - Epitopes present in the cell wall membrane and the A,B,C repeat regions of the "M" protein are immunologically similar to molecules in human myosin. tropomysin, keratin actin, laminin, vimentin. - "This molecular mimicry is the basis for autoimmune response that leads to Acute Rheumatic fever".