March8 deficiency rescues MHCII expression on cTECs and CD4 T cell selection in CD83-deficient mice. (A) March8 mRNA expression in thymic APCs (mean ± SEM of two to three biological replicates). Data are representative of two independent experiments. AU, arbitrary units; pDCs, plasmacytoid DCs. (B) Surface MHCII on cTECs from WT, Cd83^−/−, March8^−/−, and Cd83^−/−March8^−/− mice. The diagram on the right depicts the MFI of MHCII in individual mice relative to WT. Horizontal bars are mean values ± SEM from at least nine mice in each group. (C) CD4 and CD8 expression on thymocytes from mice of the indicated genotype. Values indicate the mean frequency of CD4 SP cells ± SEM among total thymocytes. Cumulative data are summarized in the graph on the right. Each data point represents an individual mouse. Data are from n ≥ 9 for each experimental group. ***, P < 0.001 (Student’s t test).