A decrease in the frequency of CD4+Foxp3+ cells was found in the lungs of infected CCR4−/− mice at 15 and 70 days of infection compared with their WT counterparts (Fig. 3d), and the number of CD4+Foxp3+ cells was significantly lower in CCR4−/− mice at 70 days of infection compared with WT mice (Fig. 3e). Here, CD4 is linked to infection.