CD4 and acute respiratory distress syndrome: The prevalence of Th17 (CD4+ IL-17A+/CD4+ T cells) in lung was significantly higher in ALI 24 h group than that in ALI 6 h group (ALI 6 h group: 1.6 ± 0.15%, ALI 24 h group: 2.7 ± 0.17%, P = 0.0006, Fig. 4).