Marked conservation of complementarity-determining region 3 of the beta-chain of TCRs recognizing a mycobacterial heat shock protein 60-derived peptide with strong sequence similarity to human heat shock protein 60.
The variable gene usage and sequence of human TCRs specific for a particular MHC/peptide combination have been investigated. The peptide comprises amino acids 456-466 of the 65-kDa Mycobacterium tuberculosis heat shock protein (hsp60), and is recognized in the context of HLA-DP. TCRs from both synovial fluid and peripheral blood (PB)-derived T cell clones used only five different V beta genes, three of which are closely related (V beta 6.7a, V beta 6.7b, and V beta 21.3). Among TCRs using these three genes there was marked conservation of the beta-chain sequence, whereby complementarity-determining region 3 (CDR3) contained an amino acid motif (*R*G*, amino acids 96-100) in association with either J beta 1.4 or J beta 2.5. These conclusions were strengthened by analysis of peptide-stimulated T cell lines that revealed not only TCR beta-chain sequences identical with those seen in T cell clones, but also additional beta-chains with similar CDR3 region sequences and J gene usage. In contrast, T cell lines derived by using IL-2 or a control peptide revealed variable usage of V beta and J beta genes; V beta 6.7a/b sequences from these lines and from freshly isolated PB did not contain the CDR3 motif noted in TCRs from Ag-specific T cells. We suggest that the remarkably limited diversity of TCRs noted in this study is a consequence of the similarity between the mycobacterial hsp60 peptide and the equivalent peptide from human hsp60, and reflects the trimming of the TCR repertoire required to maintain self-tolerance.
Goodall
J C
JC
Department of Rheumatology, Medical School, Birmingham University, United Kingdom.
Henwood
J
J
Bacon
P A
PA
Gaston
J S
JS
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000276:immunology*; D001483:Base Sequence; D018834:Chaperonin 60 / Q000737:chemistry / Q000276:immunology*; D017124:Conserved Sequence; D015329:Gene Rearrangement, T-Lymphocyte / Q000235:genetics; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000276:immunology*; D016133:Polymerase Chain Reaction / Q000379:methods; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics* / Q000276:immunology*; D012641:Selection, Genetic; D013601:T-Lymphocytes / Q000276:immunology
D000942:Antigens, Bacterial; D018834:Chaperonin 60; D007135:Immunoglobulin Variable Region; D016693:Receptors, Antigen, T-Cell, alpha-beta