IL17A and acute respiratory distress syndrome: In this study, we found that γδT cells (including the Vγ4+γδT subset) were rapidly recruited to the lungs (Figures 1E,G) and were the major source of lung IL-17A (Figures 2 and 3), which might mediate the development ALI and ARDS at the early stage during severe influenza A (H1N1) pdm09 virus infection in mice.