CD4 and acute respiratory distress syndrome: The prevalence of Th1 (CD4+ IFN-γ+/CD4+ T cells) in lung was markedly lower in ALI 24 h group than that in ALI 6 h group (ALI 6 h group: 2.1 ± 0.2%, ALI 24 h group: 1.0 ± 0.12%, P = 0.0013, Supplementary Fig. S1).