CD4 and acute respiratory distress syndrome: Based on these results, we deduced that Xuebijing has therapeutic effects on patients with ARDS partly by regulating the immune cell/cytokine pathways, such as maintaining CD4+ and CD8+ T cell balance, inhibiting p75(NTR) signaling, inhibiting CXCR4 and LPA signaling, promoting FAS (CD95) signaling, and thus inhibiting the producing and releasing of cytokines and chemokines.