LIMITED RESTRICTION IN THE TCR-ALPHA-BETA-V-REGION USAGE OF ANTIGEN-SPECIFIC CLONES - RECOGNITION OF MYELIN BASIC-PROTEIN (AMINO-ACIDS-84-102) AND MYCOBACTERIUM-BOVIS 65-KDA HEAT-SHOCK PROTEIN (AMINO-ACIDS-3-13) BY T-CELL CLONES ESTABLISHED FROM PERIPHERAL-BLOOD MONONUCLEAR-CELLS OF MONOZYGOTIC TWINS AND HLA-IDENTICAL INDIVIDUALS

We have analyzed the TCR-alpha beta repertoire specific for a given pe ptide/MHC complex by using pairs of HLA-identical individuals ranging from monozygotic twins to unrelated individuals to examine the contrib ution of genetic background and HLA expression in shaping the potentia l response to a single antigenic epitope. This panel has been previous ly defined, demonstrating that the concordance of the peripheral TCR-a lpha beta repertoires directly correlates to the level of relation and HLA identity. We have analyzed peptide-specific T cell clones derived from T cell lines from these individuals specific for MHC class II-re stricted peptides: Mycobacterium bovis 65-kDa heat shock protein (65-k Da hsp) amino acids (aa) 3-13 (DR3-restricted), and myelin basic prote in aa 84-102 (DR2-restricted). DNA sequence analysis was used to deter mine the composition of the TCR-alpha beta V regions. Although the ove rall TCR-alpha beta repertoires between individuals were diverse, an i ntra-individual limited restriction was evident. There was also a limi ted conservation in the response to the different peptides: high frequ encies of V beta 2, 4, 7, 19, V alpha 21, and J alpha 17 responded to the MBP aa84-102, whereas these V/J regions were limited or absent in the 65-kDa hsp aa3-13 repertoire. Similarly, V beta 5.1 and J alpha 9 were increased in the 65-kDa hsp aa3-13 repertoire. Within the CDR3s, motifs could be identified that were similar between twins. Furthermor e, one of these motifs resembled CDR3s previously found in correspondi ng animal models. Similarities could also be seen in the CDR3s of T ce ll clones sharing V gene usage and peptide specificity. Thus, the in v itro response to antigenic peptides seems to be quite heterogeneous ov erall and individual specific.