T cell response to myelin basic protein epitopes in multiple sclerosis patients and healthy subjects.

T cell lines and clones specific for human myelin basic protein (BP) were selected from three multiple sclerosis (MS) patients and two healthy subjects and tested for their proliferative responses to a battery of synthetic peptides, 9 to 21 amino acid residues long. The combined amino acid sequence of the peptides spanned the complete sequence of the human BP. The results suggest the development of T cells sensitized to at least four independent regions of the human BP, indicating some diversity of the human T cell repertoire to BP. However, an immunodominant T cell epitope was located in the C-terminal region, defined by residues 149-162. This epitope was recognized by T cells from three subjects out of five (one MS patient and both healthy controls) in the context of different DR specificities. Another epitope (located in the 57-75 region) which triggered one MS patient's T cell response was also recognized by a mycobacteria-specific T cell clone cross-reacting with BP.