title: Immunological cross-reactivity between Streptococcus mutans and human heart tissue examined by cross-immunization experiments.
abstract: Hyperimmunization of rabbits with Streptococcus mutans or other related cariogenic streptococci sometimes induces serum antibodies that react with human heart muscle. To determine whether antigen I/II (AgI/II), a major surface protein antigen present in most human isolates of these organisms, was responsible for inducing cross-reactive antibodies, we tested it for antigenic similarity to heart components, exploiting the ability of immune systems to mount anamnestic responses to antigens previously encountered. Mice immunized with a strain of Streptococcus pyogenes type M6, known to be heart cross-reactive, or with intact S. mutans cells developed antibodies that could be detected on a human heart sarcolemmal preparation. However, mice immunized with AgI/II and boosted with sarcolemma were unable to develop significant antisarcolemmal antibodies attributable to prior sensitization by AgI/II. Similarly, AgI/II was unable to recall antisarcolemmal responses in mice previously immunized with sarcolemma. Nevertheless, strong immunoglobulin G antibody responses to AgI/II were detected at the single-cell level in spleens and as circulating antibodies in all mice immunized with AgI/II or AgI/II-bearing S. mutans. We conclude that the ability of S. mutans to induce heart-reactive antibodies is not due to antigenic similarity between AgI/II and components of human heart but may be caused by other cross-reactive antigens in the bacterial cells or by nonspecific stimulation of the immune system.
authors.affiliation: Department of Microbiology, University of Alabama, Birmingham 35294.
authors.forename: H Y
authors.initials: HY
authors.lastname: Wu
authors.forename: M W
authors.initials: MW
authors.lastname: Russell
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D000942:Antigens, Bacterial / Q000276:immunology*; D003429:Cross Reactions; D006321:Heart / Q000382:microbiology*; D006801:Humans; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D011817:Rabbits; D012508:Sarcolemma / Q000276:immunology* / Q000382:microbiology; D013295:Streptococcus mutans / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial