The prevalence of Th1 (CD4+ IFN-γ+/CD4+ T cells) in lung was markedly lower in ALI 24 h group than that in normal control group (Con group: 3.7 ± 0.35%, ALI 24 h group: 1.0 ± 0.12%, P = 0.0003, Supplementary Fig. S1). This evidence concerns the gene CD4 and acute respiratory distress syndrome.