Fig. 1

IL-4 and anti-IL-4 antibody complex (IL-4C) treatment protects mice from lethal influenza A virus infection. IL-4 (1.5 µg) and anti-IL-4 antibody (7.5 µg) were mixed and injected intraperitoneally into mice daily for 7 days. On day 8, PBS-treated control and IL-4C-treated mice were intranasally infected with the PR8 strain of influenza A virus. A The experimental protocol. B Peripheral blood cells were collected from control and IL-4C-treated mice before (Pre) and after (D0) PBS or IL-4C administration, and the expression levels of CD44 and CXCR3 in CD8 T cells were analyzed by flow cytometry. The numbers in the dot plots are the percentages of cells in each quadrant. The data are the means ± SDs (n = 5/group); the x-numbers indicate fold changes. C The survival of influenza-infected mice was monitored daily for 15 days for the PBS control (n = 35), IL-4C (n = 35), IL-4-only (n = 5), and anti-IL-4 Ab-only treated groups (n = 5). Statistical analysis was measured using an unpaired t-test and Mantel–Cox test. n.s, not significant. *p < 0.05; ***p < 0.001