IL4 and infection: Lung CD8+ T-cell subsets were then examined at 2 and 4 days post-secondary infection: GM-CSF+ CD8+ T cells (Figures 5A,E, respectively), IL-4+ CD8+ T cells (Figures 5B,F, respectively), IFN-γ+ CD8+ T cells (Figures 5C,G, respectively), and IL-17+ CD8+ T cells (Figures 5D,H, respectively).