title: The Crohn's disease-associated bacterial protein I2 is a novel enteric t cell superantigen.
abstract: An aberrant T cell response to enteric bacteria is important in inflammatory bowel disease. However, the identity of relevant microbial antigens is unknown. Here, we report the presence of I2, a Crohn's disease-associated microbial gene, in the murine intestine. The I2 protein induced a proliferative and IL-10 response by CD4(+) T cells from unimmunized mice. The I2 response was dependent on MHC class II-mediated recognition but did not require antigen processing. Selective activation was observed for the TCR-Vbeta5 subpopulation. These findings indicate that the I2 protein is a new class of T cell superantigen and suggest that colonization by the I2 microorganism in susceptible hosts may provide a superantigenic stimulus pertinent to Crohn's disease pathogenesis.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California, Los Angeles, School of Medicine, Los Angeles, CA 90095, USA.
authors.forename: H
authors.initials: H
authors.lastname: Dalwadi
authors.forename: B
authors.initials: B
authors.lastname: Wei
authors.forename: M
authors.initials: M
authors.lastname: Kronenberg
authors.forename: C L
authors.initials: CL
authors.lastname: Sutton
authors.forename: J
authors.initials: J
authors.lastname: Braun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D001426:Bacterial Proteins / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003424:Crohn Disease / Q000209:etiology / Q000276:immunology*; D016753:Interleukin-10 / Q000378:metabolism; D007422:Intestines / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D018089:Superantigens / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D001426:Bacterial Proteins; D018089:Superantigens; D016753:Interleukin-10