T cell epitopes of human myelin oligodendrocyte glycoprotein identified inHLA-DR4 (DRBI*0401) transgenic mice are encephalitogenic and are presentedby human B cells

Myelin oligodendrocyte glycoprotein (MOG) is an Ag present in the myelin sh eath of the CNS thought to be targeted by the autoimmune T cell response in multiple sclerosis (MS). In this study, we have for the first time charact erized the T cell epitopes of human MOG restricted by HLA-DR4 (DRB1*0401), an MHC class II allele associated with MS in a subpopulation of patients. U sing MHC binding algorithms, we have predicted MOG peptide binding to HLA-D R4 (DRB1*0401) and subsequently defined the in vivo T cell reactivity to ov erlapping MOG peptides by testing HLA-DR4 (DRB1*0401) transgenic mice immun ized with recombinant human (rh)MOG. The data indicated that MOG peptide 97 -108 (core 99-107, FFRDHSYQE) was the immunodominant HLA-DR4-restricted T c ell epitope in vivo. This peptide has a high in vitro binding affinity for HLA-DR4 (DRB1*0401) and upon immunization induced severe experimental autoi mmune encephalomyelitis in the HLA-DR4 transgenic mice. Interestingly, the same peptide was presented by human B cells expressing HLA-DR4 (DRB1*0401), suggesting a role for the identified MOG epitopes in the pathogenesis of h uman MS.