title: Cross-reactive TCR responses to self antigens presented by different MHC class II molecules.
abstract: Autoreactive T cells represent a natural repertoire of T cells in both diseased patients and healthy individuals. The mechanisms regulating the function of these autoreactive T cells are still unknown. Ob1A12 is a myelin basic protein (MBP)-reactive Th cell clone derived from a patient with relapsing-remitting multiple sclerosis. Mice transgenic for this human TCR and DRA and DRB1*1501 chains develop spontaneous experimental autoimmune encephalomyelitis. The reactivity of Ob1A12 is reported to be restricted to recognition of MBP peptide 85-99 in the context of DRB1*1501. DRA/DRB1*1501 and the patient's other restriction element, DRA/DRB1*0401, differ significantly in their amino acid sequences. In this study we describe an altered peptide ligand derived from MBP(85-99) with a single amino acid substitution at position 88 (Val to Lys; 88V-->K), that could stimulate the Ob1A12.TCR in the context of both DRA/DRB1*1501 and DRA/DRB1*0401. Analysis of a panel of transfected T cell hybridomas expressing Ob1A12.TCR and CD4 indicated that Ob1A12.TCR cross-reactivity in the context of DRA/DRB1*0401 is critically dependent on the presence of the CD4 coreceptor. Furthermore, we found that activation of Ob1A12.TCR with MBP altered peptide ligand 85-99 88V-->K presented by DRB1*1501 or DRB1*0401 resulted in significant differences in TCR zeta phosphorylation. Our data indicate that injection of altered peptide ligand into patients heterozygous for MHC class II molecules may result in unexpected cross-reactivities, leading to activation of autoreactive T cells.
authors.affiliation: Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Marcin P
authors.initials: MP
authors.lastname: Mycko
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Waldner
authors.forename: David E
authors.initials: DE
authors.lastname: Anderson
authors.forename: Katarzyna D
authors.initials: KD
authors.lastname: Bourcier
authors.forename: Kai W
authors.initials: KW
authors.lastname: Wucherpfennig
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Kuchroo
authors.forename: David A
authors.initials: DA
authors.lastname: Hafler
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D017951:Antigen Presentation; D001324:Autoantigens / Q000276:immunology*; D015704:CD4 Antigens / Q000276:immunology; D003429:Cross Reactions; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology*; D059805:HLA-DR alpha-Chains; D059811:HLA-DRB1 Chains; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D007739:L Cells; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000276:immunology*; D004676:Myelin Basic Protein / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014162:Transfection
chemical_list: D001324:Autoantigens; D015704:CD4 Antigens; D006684:HLA-DR Antigens; D059805:HLA-DR alpha-Chains; D059811:HLA-DRB1 Chains; C553505:HLA-DRB1*04:01 antigen; C489631:HLA-DRB1*15:01 antigen; D008565:Membrane Proteins; D004676:Myelin Basic Protein; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; C054979:antigen T cell receptor, zeta chain; C107908:myelin basic protein 85-99