Th17 polarized T cell lines have shorter TCRVαCDR3 length and higher tetramer binding avidity than Th1 and Th2 polarized cell lines. Highly polarized Th1 (n = 6), Th17 (n = 6) and Th2 (n = 6) T cell lines derived from the same peptide immunizations of NOD.E mice were maintained in culture through four re-stimulations in vitro. Cells were analyzed for cytokine production and H2-Ag7/PLP 56-70 tetramer binding avidity. At the first re-stimulation (Day 10), IL-17 production and high avidity tetramer binding by the Th17 cell lines are noted (A, C). At the fourth re-stimulation (Day 40), IL-17 production and tetramer binding avidity of the Th17 cell lines have decreased (B, D) and the cytokine profile and tetramer binding characteristics now resemble those of the Th1 cell lines. (E) The TCRVαCDR3 chain repertoire of Th17 cells at the first (left hand panel) and fourth (right hand panel) re-stimulations were analyzed. The frequency (%) of each unique TCR sequence identified is shown. The mean TCRVαCDR3 lengths for the first and fourth re-stimulations are 10.95 ± 0.22 (SE) (n = 37) and 11.39 ± 0.21 (SE) (n = 51), respectively. The difference in mean CDR3α length between the first and fourth re-stimulation is statistically significant (P = 0.038) and shows progression to a TCR repertoire with longer CDR3α regions as cells lose their IL-17 producing phenotype and become more Th1 like in their tetramer binding characteristics and cytokine production.