CD83 regulation of MARCH 8 activity is critical for CD4⁺ T cell selection. (A) MHC II expression on cTECs and mTECs from Cd83^anu/anu, March8^−/−, and Cd83^anu/anu × March8^−/− mice. Histograms are representative of two independent experiments. (B) Frequency of CD4⁺ T cells in peripheral blood lymphocytes of wild-type, Cd83^anu/anu, March8^−/−, and Cd83^anu/anu × March8^−/− mice. Each symbol represents an individual mouse. (C) Thymic CD4 versus CD8 profiles in CD3⁺ thymocytes of CD83^anu/anu, March8^−/−, and Cd83^anu/anu × March8^−/− mice. (D) Spleen CD4 versus CD8 profiles in CD3⁺ splenic T cells of Cd83^anu/anu, March8^−/−, and Cd83^anu/anu × March8^−/− mice. (C and D) The graphs display data from two independent experiments. Each symbol represents an individual mouse. Bars indicate the mean. **, P < 0.01; ***, P < 0.001, one-way ANOVA followed by Tukey's multiple comparison test.