CHARACTERIZATION OF THE IMMUNE-RESPONSE TO A SECONDARY ENCEPHALITOGENIC EPITOPE OF BASIC-PROTEIN IN LEWIS RATS .2. BIASED T-CELL RECEPTOR V-BETA EXPRESSION PREDOMINATES IN SPINAL-CORD INFILTRATING T-CELLS

The immune response of Lewis rat lymph node T cells to guinea pig myelin basic protein (GP-BP) in experimental allergic encephalomyelitis is directed primarily against a region of basic protein encompassed by residues 72-89. T cells that respond to this epitope are restricted by the RT1.B1 class II molecule of the MHC and use V-beta-8.2 exclusively in their TCR. A second region of GP-BP, residues 87-99, also induces experimental allergic encephalomyelitis in Lewis rats but this response is restricted primarily by RT1.D1. Elsewhere we describe the biologic characteristics of T cell clones responding to the synthetic peptide, s87-99, and to a related peptide, s85-99. We present a detailed analysis of TCR V-beta-gene expression among these clones, derived from the lymph node and spinal cord of immunized animals, and among spinal cord derived T cell clones reactive to GP-BP 72-89. We find that spinal cord-derived clones, reactive to s85-99 and to s87-99, use V-beta-6 predominately. In contrast, T cell clones derived from lymph nodes and reactive to the same peptides express multiple V-beta genes including V-beta-6. This difference in heterogeneity of V-beta usage at the clonal level is also seen in T cell lines derived from spinal cord and immune lymph node. DNA sequence comparison of the CDR3 regions in V-beta-6+ spinal cord clones revealed a conserved amino acid motif also found in the majority of V-beta-6 sequences from the spinal cord anti-s85-99 line. Although V-beta-6 was expressed in some lymph node-derived clones, only one contained a CDR3 region similar-to that seen in spinal cord isolates. All spinal cord-derived T cell clones reactive to GP-BP 72-89 used V-beta-8.2 and most (five of six) contained the AspSer residues in CDR3 previously shown to be associated with V-beta-8.2 receptors expressed by the majority of lymph node T cells responding to GP-BP 72-89. These data indicate that TCR V-beta usage in peripheral T cells responding to an autoantigen does not always predict the V-beta usage among T cells at the site of an autoimmune attack. Possible explanations for the relative homogeneity in TCR V-beta expression seen in T cell clones derived from the spinal cord are discussed.