T cell receptor α-chain usage can determine ant igen-selected tcr 3-chain repertoire diversity

Certain antigen-specific responses can give rise to simple V-region bias in the T cell receptor (TCR) repertoire while others can be dominated by a single TCR donotype repeatedly isolated from different individuals. Cytotoxic T lymphocytes (CTL) specific for a K ^b -binding determinant from the Herpes Simplex Virus (HSV) glycoprotein B (gB), preferentially express a dominant Vβ10 TCR γ-chain subset with extensive junctional conservation. We examined the contribution of the TCR α-chain to the diversity of the gB-specific CTL response. The TCR γ-cliains were found to exhibit minimal bias in either their sequence selection or their preferential /3-chain pairing. When the gB-specific CTL were forced to use a single TCR a-chain, the T cells exhibited a severely limited form of β-chain selection. The response was now dominated by a single Vβ10 β-chain sequence (Vβ10/Jβ2.6) which showed a conserved junctional motif found in the more diverse non-transgenic T cell population.