CDR3α Sequences Can Regulate the Specificity of the Vβ8.2 CDR2 β48 Interaction with pMHC. IL-2 production of T cell hybridomas expressing the (A, D) J809.B5, (B, E) J809.H1 or (C, F) 14.C6 TCRs, or TCRs carrying amino acid substitutions at the TCR CDR2β residue Y48, in response to titrating concentrations of 3K peptide presented by IAb expressing fibroblasts. IL-2 secretion is reported as Units/mL. (D–F) The EC50 values for 3K dose responses shown in panels A–C and error bars represent the SEM of three independent experiments.