Chemokine-driven thymic egress is specific to CCR5. WT and CXCR3−/− mice were sacrificed at days 0 and 7 postinfection to quantify the number of CD4+ Foxp3+ cells in the lungs, thymus, and mediastinal lymph nodes (A). RNA was extracted from the thymus and lymph nodes of uninfected mice to measure expression of KLF2 and S1P1 by quantitative real-time PCR. HPRT was used as an endogenous control, and values represent log increase compared with WT controls (B). Data represent the mean ± SEM (n = 6–8) from two to three experiments. *p < 0.05, **p < 0.01, ##p < 0.001.