CD4 and injury: Since CD4+CD25+Foxp3+ Tregs play crucial roles in the TGF-β mediated regulation of immune response in acute lung injury (D'Alessio et al., 2009), we next analyzed the levels of CD4+CD25+Foxp3+ Tregs in the peripheral blood from sham, LPS-instilled, and LPS-instilled QD-treated mice.