Related Experiment Videos
Human IgG and Streptococcus mutans SR protein contain cross-reactive epitopes
D Wachsmann1, F Ackermans, C Vincenzotto
1National Institute of Health and Medical Research U157, Faculty of Dentistry, Strasbourg, France.
Journal of Immunology (Baltimore, Md. : 1950)
|December 15, 1989
Summary
Streptococcus mutans SR protein shares autoimmune epitopes with human IgG, potentially explaining elevated anti-IgG antibody levels after immunization. This mimicry may contribute to cross-reactivity with heart components.
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Streptococcus mutans Antigen B mediates bacterial adherence and is linked to heart cross-reactivity.
- Elevated anti-IgG antibodies are observed in rabbits immunized with S. mutans SR protein or recombinant SR (rSR).
Purpose of the Study:
- To investigate the mechanism behind elevated anti-IgG antibodies in rabbits immunized with S. mutans SR protein.
- To determine if S. mutans SR protein shares epitopes with human IgG, potentially explaining autoimmune cross-reactivity.
Main Methods:
- Immunoblots and ELISA analyses were used to detect antibody binding.
- Competition assays and experiments with biotinylated human IgG were performed to elucidate cross-reactivity mechanisms.
Main Results:
- Anti-IgG antibodies recognize common epitopes on SR, rSR, and human IgG2/IgG4, likely on the Fab region.
- Cross-reactions between IgG and SR were not mediated by an FcR mechanism.
- S. mutans SR protein exhibits molecular mimicry with human IgG, confirmed by direct competition assays.
Conclusions:
- S. mutans SR protein and human IgG heavy chains share autoimmune epitopes.
- These shared epitopes may induce anti-IgG antibodies, explaining elevated levels observed after immunization with S. mutans components.