Self-recognition and the biased mature repertoire in TCR β transgenic mice: the exception that supports the rule

Detailed sequence analysis of the companion α chains in several T-cell receptor (TCR) β chain transgenic mice have shown that the mature α chain repertoires of CD4+ T cells are biased toward the parental TCR α chain sequences. These studies further indicate that it is self-peptide–self-MHC recognition during positive intrathymic selection that biases the structure of the mature TCR α chain repertoire. To further establish the causative relationship, it is important to examine whether such a bias can be abolished when positive selection is absent. The human collagen IV-I-As complex-specific KB TCR cannot be positively selected on the self-peptide–self-MHC complexes present in the I-As strain. Therefore, the KB TCR β chain transgenic mice offer a unique opportunity for addressing this issue.