CD4 and infection: Using our T cell gating strategy (Supplemental Figure 4), we found that CD4+ and CD8+ T cells were significantly increased in both number and proportion in the lungs of μMT compared with WT mice, during both F/F infection and F/F/S infection, with CD4+ and CD8+ T cells decreased in the lung as a result of MRSA challenge (Figure 2, A–C, and Supplemental Figure 5, A–C).