CD4 and infection: However, the significant number of neutrophils at day 2 and 4, and CD4+ T cells at day 8, of Peli1−/− animals in BALF (Figures 8A,F) was not seen in lung tissue (Figures 9A,F), and the significant increase in alveolar macrophages in these animals (Figure 8B) was not observed until day 4 post-infection in lung tissue (Figure 9B).