T-cell receptor repertoires utilized in response to linear peptides representing an immunodominant MHC class II restricted T-cell epitope are far more diverse than that utilized in response to the same epitope in the nominal antigen.

Previous analyses of the T-cell receptor (TCR) repertoire utilized in response to the 1-102 fragment of the lambda cI repressor protein and specific for the immunodominant amino acid 12-26 region in the context of I-Ek, have shown this repertoire to be extremely restricted. In contrast, here we show that the TCR repertoires utilized in two strains of I-Ek expressing mice in response to two linear peptides representing this immunodominant region are diverse. Despite their extensive diversity, these repertoires are somewhat overlapping.