CD4 and infection: Interestingly, whereas the levels of pro-inflammatory cytokines in sera were similar in both mice groups (data not shown), the levels of IL-10 in sera and the % of IL-10-producing cells were significantly higher in AhRd vs. WT mice during the acute phase of the infection (Figures 4E,F), being a CD4+ cell population the main producer of this cytokine at day 10 pi (Figure 4F).