Interleukin 17A (IL-17A) is the founding member of the family of cytokines that includes IL-17B through IL-17F. It is a potent pro-inflammatory cytokine that plays a key role in defense against pathogens. IL-17A and IL-17F signal as homodimers or heterodimers through the same receptor, and activate NF-κB, MAPK, and C/EBP pathways. IL-17A mediates protection against extracellular pathogens, and together with IL-22 stimulates production of antimicrobial peptides. It induces granulopoiesis factors and neutrophil-specific chemokines. Together with tumor necrosis factor alpha (TNF-α), IL-17A induces a sustained neutrophil recruitment during inflammation.
