CD4 and acute respiratory distress syndrome: The prevalence of Th17 (CD4+ IL-17A+/CD4+ T cells) in peripheral blood was significantly higher in ALI 24 h group than that in normal control group (Con group: 0.9 ± 0.06%, ALI 24 h group: 2 ± 0.4%, P = 0.004, Fig. 4).