PF4 and acute respiratory distress syndrome: About the CXCL pathway signals in the sepsis-related ARDS, we see that it signals in the direction of platelets, RBCs and monocytes acting on Th cells, with the strongest signals emitted by platelets (Figures 7L-N, Supplementary Figures S8K, L), and the ligand receptor that plays a role within its pathway is PF4-CXCR3 (Figure 7O).