CD4 and infection: Very few splenic CD4+Foxp3+ T cells expressed IFN-γ in naïve or malaria-infected WT or WSX-1−/− mice and there was only a transient difference in the frequencies and numbers of CD4+Foxp3+ IFN-γ+ cells in WT and WSX-1−/− mice on day 9 of infection (Figure 7F–H).