CD4 and acute respiratory distress syndrome: The prevalence of Treg (CD4+ CD25+ Foxp3+/CD4+ T cells) in peripheral blood was markedly lower in ALI 24 h group than that in normal control group (Con group: 5.2 ± 0.8%, ALI 24 h group: 2.4 ± 0.3%, P = 0.0022, Fig. 5).