FOXN1 and infection: After infection with influenza virus, the number of influenza-specific CD8+ T cells in the lung and spleen were reduced by approximately 50% in young FoxN1 K14KO and aged WT mice, compared to young control mice (Figures 3A and B), indicating that FoxN1 deletion and aging have similar effects in reducing antigen-specific responses, perhaps because of reduced availability of naïve T-cells.