Mouse Interleukin17A/F is a heterodimer contains two subunits A and F. IL-17A subunit has 158 amino acids (molecular weight 21 kDa), IL-17F subunit has 50% similarity to A. All IL-17 cytokines have a similar protein structure, and no sequence similarity to any other cytokines. These cytokines are well conserved in mammals, with significant sequence conservation between the human and mouse homologs. A major role of IL-17 is its involvement in inducing and mediating proinflammatory responses. It acts as potent mediator in delayed-type reactions by increasing chemokine production in various tissues to recruit monocytes and neutrophils to the site of inflammation, similar to interferon gamma. IL-17 is produced by T-helper cells and is induced by IL–23 which results in destructive tissue damage in delayed-type reactions. IL-17 induces the production of many other synergistic cytokines, including GM-CSF, IL-6, IL-1b, and TNFa. The IL-17 family has been linked to many immune/autoimmune related diseases including rheumatoid arthritis, asthma, lupus, allograft rejection, anti-tumor immunity and recently Psoriasis. Because of its involvement in autoimmune conditions, IL-17 inhibitors are being investigated as possible treatments.