Antibody response to non-streptococcal antigens as related to rheumatic fever susceptibility.

It is now well established that practically all initial attacks and subsequent recurrences of rheumatic fever are precipitated by antecedent Group A hemolytic streptococcal infection. Evidence to support this concept has been based on the close epidemiologic and bacteriologic association of acute rheumatic fever and streptococcal infection (1-9) as well as on the striking similarity of the antibody responses in both of these conditions (10). Despite this dependence of the rheumatic state upon prior hemolytic streptococcal infection, only a small portion of those exposed to this group of organisms actually develop rheumatic fever. Such disparity in the disease incidence indicates the importance of the host factor and suggests that susceptibility variables are important determinants of pathogenesis of rheumatic fever. The purpose of this report is to explore the possibility that there exists in subjects with rheumatic fever a peculiarity of immune response which predisposes to the rheumatic state. Others have shown that hemolytic streptococcal respiratory infection complicated by rheumatic fever is associated with higher mean antistreptococcal antibody titers than is the uncomplicated illness (11, 12), and the conclusion from such data has Deen that an immunologic hyperreactivity in such susceptible individuals may be fundamental for the development of rheumatic fever. Our studies have aimed to determine whether such supposed immunologic hyperreactivity of rheumatic subjects is confined to the streptococcus alone or whether one may also detect a more general augmentation of antibody response to non-streptococcal antigens as well. Preliminary results of such studies have been