PF4 and acute respiratory distress syndrome: For example, CCL5 and CXCL4 heterodimers are elevated in ARDS and in mouse models of lung injury, while destabilising these complexes reduced sepsis and LPS-induced lung injury in mice.35 Although CXCL8, and most other chemokines, can form homodimers and even tetramers, the different three-dimensional configuration of CXC-chemokines compared with CC-chemokines makes heterodimer formation between family members more likely than mixed CXC-CC heterodimers.36 For example, CXCL8 readily forms a heterodimer with CXCL4 (platelet factor 4), while CCL2 can form heterodimers with CCL5 and CCL8.