Single amino acid replacements in an antigenic peptide are sufficient to alter the TCR V beta repertoire of the responding CD8+ cytotoxic lymphocyte population.
Cytotoxic CD8+ T lymphocytes are activated upon the engagement of their Ag-specific receptors by MHC class I molecules loaded with peptides 8-11 amino acids long. T cell responses triggered by certain antigenic peptides are restricted to a limited number of TCR V beta elements. The precise role of the peptide in causing this restricted TCR V beta expansion in vivo remains unclear. To address this issue, we immunized C57BL/6 mice with the immunodominant peptide of the vesicular stomatitis virus (VSV) and several peptide variants carrying single substitutions at TCR-contact residues. We observed the expansion of a limited set of TCR V beta elements responding to each peptide variant. To focus our analysis solely on the TCR beta-chain, we created a transgenic mouse expressing exclusively the TCR alpha-chain from a VSV peptide-specific CD8+ T cell clone. These mice showed an even more restricted TCR V beta usage consequent to peptide immunization. However, in both C57BL/6 and TCR alpha transgenic mice, single amino acid replacements in TCR-contact residues of the VSV peptide could alter the TCR V beta usage of the responding CD8+ T lymphocytes. These results provide in vivo evidence for an interaction between the antigenic peptide and the germline-encoded complementarity-determining region-beta loops that can influence the selection of the responding TCR repertoire. Furthermore, only replacements at residues near the C terminus of the peptide were able to alter the TCR V beta usage, which is consistent with the notion that the TCR beta-chain interacts in vivo preferentially with this region of the MHC/peptide complex.
Kalergis
A M
AM
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Ono
T
T
Wang
F
F
DiLorenzo
T P
TP
Honda
S
S
Nathenson
S G
SG
D019943:Amino Acid Substitution / Q000276:immunology*; D000818:Animals; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D018984:Epitopes, T-Lymphocyte / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D005810:Multigene Family / Q000276:immunology; D019251:Nucleocapsid / Q000008:administration & dosage / Q000138:chemical synthesis / Q000276:immunology; D019590:Nucleocapsid Proteins; D009842:Oligopeptides / Q000008:administration & dosage / Q000138:chemical synthesis / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism*
D018984:Epitopes, T-Lymphocyte; D019590:Nucleocapsid Proteins; D009842:Oligopeptides; D016693:Receptors, Antigen, T-Cell, alpha-beta