WT, TNFR1−/−, and TNFR2−/− mice were infected with a sub-lethal dose of influenza virus. (A) Weight loss was monitored daily and the percent baseline weight change for day 8 post-infection was calculated. (B) ELISA was used to determine the levels of albumin in the BALF 8 days post-infection. (C) The total number of viable cells recovered from BAL day 8 post-infection. Flow cytometry was used to analyze the total number of (D) CD8+, (E) NP366–374-specific CD8+, and (F) CD107a+CD8+ T cells. Data represent mean ± standard deviation. Each group consists of 4–6 mice. Data are representative of at least two independent experiments. *P<0.05, **P<0.01, ***P<0.005.