SummaryWe have examined previously the peptide specificity of the T cell response to myelin basic protein (MBP) in patients with multiple sclerosis (MS) and healthy controls, and demonstrated that an epitope spanning amino acids 87-106 was frequently recognized. Because this region is encephalitogenic in some experimental animals, it has been postulated that the response to the epitope may have relevance to MS. In this study, the fine specificity of this response is studied using four well-characterized, monospecific T cell lines from three MS patients and an identical twin of a patient. Each of the lines recognized a peptide with the same core sequence, amino acids 89-99, although the responses were affected to various degrees by truncations at the 000H-or NH2 terminal ends of the 87-106 epitope. Importantly, the epitope was recognized in conjunction with four different HLA-DR molecules. Also, the T cell receptor /3 chain usage was heterogeneous, and each line expressed a different VDJ sequence. The four HLADR molecules restricting the response to this epitope have been shown to be overrepresented in MS populations in various geographic areas, suggesting that the response to this region of the MBP molecule may be relevant to the pathogenesis of MS. These findings may have important implications in designing therapeutic strategies for the disease .Although the cause of multiple sclerosis (MS)' is not 13. known, a T cell-mediated autoimmune process has been postulated. Myelin basic protein (MBP) is a potential target antigen because it induces experimental allergic encephalomyelitis (EAE) in susceptible animals. Encephalitogenic epitopes of MBP differ among susceptible strains and correlate with the MHC class II genotype (1) . The TCRs expressed by encephalitogenic T cells from PL/J and B10YL mice and Lewis rats use the same TCR V(3 chain, V08 .2, and have similarities in their VDJ regions, as reviewed in reference 2. Thus, the pathogenesis of EAE is related to the capacity of T cells with the appropriate TCRs to recognize epitopes of MBP 1 Abbreviations used in this paper. aa, amino acid ; EAE, experimental allergic encephalomyelitis ; HTC, homozygous typing cells; ICAM-1, intracellular adhesion molecule 1; MBP, myelin basic protein; MS, multiple sclerosis ; TCL, T cell line . 19presented in conjunction with class II MHC molecules . These requirements have provided rationales for therapeutic strategies that prevent or treat EAE (3-7).The analysis of the T cell response to MBP in patients with MS and in healthy controls has shown that several regions of the molecule are frequently recognized (8-10). One region, an epitope spanning amino acids (aa) 87-106, was recognized by >50% of T cell lines (TCL) derived from both MS patients and controls (9) . Our findings indicated that several HLADR molecules could serve as restriction elements for MBP or fragments of the molecule . In contrast, other investigators have reported that an epitope spanning as 84-102 is predominantly recognized by TCL from MS patients and large...

Although the cause of multiple sclerosis (MS) is unknown, it is thought to involve a T cell-mediated autoimmune mechanism. Susceptibility to the disease is influenced by genetic factors such as genes of the HLA and T-cell receptor (TCR) complex. Other evidence for a genetic influence includes the low incidence in certain ethnic groups, the increased risk if there are affected family members and the increased concordance rate for disease in monozygotic twin pairs (26%), compared to dizygotic twins. Epidemiological studies indicate that there may be an additional role for environmental factors. Although the target antigen(s) are not yet identified, several myelin or myelin-associated proteins have been suspected, among them myelin basic protein. A lack of genetically comparable controls has impaired the analysis of the T-cell response in MS patients and caused disagreement on TCR usage in the disease. Here we analyse the role of TCR genes in MS by comparing TCR usage in discordant versus concordant monozygotic twins in response to self and foreign antigens. We find that after stimulation with myelin basic protein or tetanus toxoid, control twin sets as well as concordant twin sets select similar V alpha chains. Only the discordant twin sets select different TCRs after stimulation with antigens. Thus exogenous factors or the disease shape the TCR repertoire in MS patients, as seen by comparison with unaffected genetically identical individuals. This skewing of the TCR repertoire could contribute to the pathogenesis of MS and other T-cell-mediated diseases.

Multiple sclerosis (MS) l is a chronic demyelinating disease of the central nervous system (CNS) which can have a highly variable clinical course. While the etiology of this disorder is unknown, the majority of current research in this field is focussed on the elucidation of an infectious agent, an autoimmune process, or a combination of the two (1, 2). Numerous studies (1-4) have demonstrated immune abnormalities in MS. However, the majority of these reports have employed assays that either measured an aspect of cellular recognition without consideration of function (eg. lympboproliferative assays), or assessed the function of antigen-nonspecific cell activity, such as natural killer (NK) cell activity. Little is known of those populations of cells that are antigen-specific and have a demonstrable function, such as cytotoxic T cells (CTL) or T helper cells, which regulate T or B cell functions.Measles virus has been considered as a possible etiological factor in the pathogenesis of MS, based primarily on serological findings (5-8). For the most part, assays designed to demonstrate a functional cellular immune response to this agent (eg. CTL) have been unsuccessful, and consequently, the assessment of such antigen-specific immune responses in MS patients has not been possible. Using T cell clones (9, 10) and bulk culture populations (lacobson, S., M. L. Flerlage, and H. F. McFarland, manuscript in preparation) 2, we have shown that measles virus-specific CTL have a cell surface phenotype that was OKT4 +, and that they lysed infected cells by recognition of measles virus antigen in association with HLA class II molecules. To determine whether a measles virus-specific cellular immune abnormality is associated with MS, we analyzed the capacity of lymphocytes from MS patients to generate measles virus-specific CTL. In comparison, we have studied normal individuals and other disease controls (ODC). The vast majority of MS patients either failed to generate measles virus-specific CTL, or had significantly lower CTL responses than either normal individuals or ODC. Moreover, this decreased CTL response in MS patients was specific for This work was supported by postdoctoral fellowship grant FG 573 A-1 awarded to S. Jacobson from the National Multiple Sclerosis Society.a Abbreviations used in this paper: CNS, central nervous system; CTL, cytotoxic T ]ympbocytes; DSS, Kurtzke Disability Scale; EBV, Epstein-Barr virus; MS, multiple sclerosis; NK, natural killer; ODC, other disease controls; PBL, peripheral blood lymphocytes.~ Jacobson, S., and H. F. . Studies of measles virus specific, HLA class II restricted cytotoxic T lymphocytes generated in bulk culture. Abstract, Symposium on the Pathobiology and Immunopathology of Virus Infection Sendai, Japan.

Although multiple sclerosis (MS) is thought to be an autoimmune disease, the target antigen of the immune response is unknown. Both myelin basic protein (MBP) and proteolipid protein (PLP) have been considered candidate autoantigens. Because the immune response to either foreign or self antigens is influenced by the genetic background of the host, the importance of these candidate antigens has been difficult to establish in humans because of genetic diversity. To eliminate genetic differences in MS patients and healthy controls, we have studied the MBP-specific T-cell response in 6 sets of identical twins, 3 of which were concordant and 3 discordant for MS. A total of 638 short-term T-cell lines were established and characterized for MBP-specific proliferative and cytotoxic activity, fine specificity, and human leukocyte antigen (HLA) restriction. Similar frequencies of MBP-specific T cells were observed in affected and unaffected individuals. A slightly higher percentage of cytotoxic T-cell lines was found in affected individuals. For most of the cell lines, the restriction elements were the HLA class II antigens that have been reported previously to be associated with MS; no important differences with respect to HLA restriction were found between the patients and healthy individuals. The peptide epitopes of MBP that were recognized most frequently by the T-cell lines were those previously shown to be immunodominant. Differences in specificity were seen in some discordant twins indicating that, despite genetic identity, the MBP-specific T-cell repertoire may be shaped differently. These findings indicate that differences in frequency, peptide specificity, or HLA restriction are not sufficient to implicate MBP-specific T cells in the pathogenesis of MS. However, the T-cell response to MBP may still represent one necessary component with disease occurring when this response is combined with other host characteristics such as regulation of cytokine-, adhesion molecule-, or HLA-antigen expression in the nervous system or immunoregulatory mechanisms.