title: T cell mimicry and epitope specificity of cross-reactive T cell clones from rheumatic heart disease.
abstract: Mimicry between streptococcal M protein and cardiac myosin is important in the pathogenesis of rheumatic heart disease. M protein-specific human T cell clones derived from rheumatic carditis were cross-reactive with human cardiac myosin, and laminin, a valve protein. Among the 11 CD4(+) and CD8(+) cross-reactive T cell clones, at least 6 different reactivity patterns were distinguished, suggesting different degrees of cross-reactivity and a very diverse T cell repertoire. The latter was confirmed by a heterogeneous Vbeta gene and CDR3 usage. HLA restriction and Th1 cytokine production in response to rM6 protein were preserved when the T cell clones were stimulated by human cardiac myosin or other alpha-helical proteins, such as tropomyosin and laminin. The cross-reactive human T cell clones proliferated to B2 and B3A, dominant peptide epitopes in the B repeat region of streptococcal M protein. In human cardiac myosin, epitopes were demonstrated in the S2 and light meromyosin regions. In our study, T cell mimicry was defined as recognition of structurally related Ags involved in disease and recognized by the same T cell. Mimicry in our study was related to alpha-helical coiled coil proteins which have a repetitive seven-aa residue periodicity that maintains alpha-helical structure and thus creates a high number of degenerate possibilities for recognition by T cells. The study of human T cell clones from rheumatic heart disease revealed potential sites of T cell mimicry between streptococcal M protein and human cardiac myosin and represents some of the most well-defined T cell mimicry in human autoimmune disease.
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
authors.forename: Nadia M J
authors.initials: NM
authors.lastname: Ellis
authors.forename: Ya
authors.initials: Y
authors.lastname: Li
authors.forename: William
authors.initials: W
authors.lastname: Hildebrand
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Fischetti
authors.forename: Madeleine W
authors.initials: MW
authors.lastname: Cunningham
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D024722:Cardiac Myosins / Q000276:immunology; D002352:Carrier Proteins / Q000276:immunology; D002450:Cell Communication / Q000276:immunology*; D002460:Cell Line; D002999:Clone Cells; D016207:Cytokines / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D018716:Molecular Mimicry / Q000276:immunology*; D008969:Molecular Sequence Data; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D012214:Rheumatic Heart Disease / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D018417:Th1 Cells / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D006680:HLA Antigens; D011948:Receptors, Antigen, T-Cell; C014689:streptococcal M protein; D024722:Cardiac Myosins