CD4 and infection: The slow increase of MHC II+ macrophages and dendritic cells between 40 and 50 days of infection, was associated with an increase number of CD4+ T cells producing IFN-γ and IL-17 increased arriving in the lungs at this later time range, whereas there was only a modest increase in the number of CD8+ T cells that produced IFN-γ (Figure 4D).