CD8A and infection: After day 20 post-infection both wild type and IL-4Rα−/− neonates had an influx of activated (CD44hiCD62Llo) T cells into the lungs, however, IL-4Rα−/− neonates had significantly more activated CD4+ cells and CD8+ cells within the lungs as compared to wild type neonates at days 27 and 33 post-infection (Figure 6D,E).