CCR4 deficiency impairs deletion of OT-II thymocytes to an endogenous antigen and alters the TCR repertoire of polyclonal thymocytes. (A) Representative flow cytometry plots of CD3 versus CD69 within the DP thymocyte compartment of Ccr4^+/+ OT-II and Ccr4^−/− OT-II mice. (B) Quantification of the percentage of CD69⁺CD3⁺ cells within the DP compartment of the indicated strains, calculated from data as in A. Means + SEM compiled from two independent experiments with a total of six mice per group. (C) Comparison of TCRVβ usage in the indicated thymocyte subsets of Ccr4^+/+ versus Ccr4^−/− mice. Means + SEM compiled from three independent experiments with a total of 10 mice per group. *, P < 0.05; ***, P < 0.001 (unpaired Student’s t test).