In the lung tissue of both wild type and knockout animals, influenza A infection resulted in a transient increase in neutrophils and monocytes, similar to that seen in the BALF, as well as an increase in CD4+ and CD8+ T cells, dendritic cells, and Th17 (CD4+IL17A+) cells, at 8 days post-infection; again similar to BALF. Here, CD4 is linked to infection.