The prevalence of Treg (CD4+ CD25+ Foxp3+/CD4+ T cells) in peripheral blood was markedly lower in ALI 24 h group than that in ALI 6 h group (ALI 6 h group: 3.5 ± 0.3%, ALI 24 h group: 2.4 ± 0.3%, P = 0.014, Fig. 5). This evidence concerns the gene CD4 and acute respiratory distress syndrome.