No significant differences were observed in the frequencies of CD4+ T cells producing IFN-γ and IL-22 that were present within intraepithelial (IEL) and lamina propria (LPL) lymphocytes isolated from the small intestine of WT and Crtam−/− mice after infection with T. gondii; however, considerably fewer CD4+ T cells producing IL-17 were detected in Crtam−/− mice (Figures 2A–C). Here, CD4 is linked to infection.