CD4 and acute respiratory distress syndrome: According to research, in mice and humans with ALI, the recruitment of CD4 + CD25 + FOXP3+ Treg cells in the alveoli, particularly through the leukotriene B4(LTB4)‐leukotriene B4 receptor (BLT1) pathway,199 could decrease lung fibroproliferation200 and improve lung inflammation.201