Il17a is a pro-inflammatory cytokine as a member of the interleukin-17 family. It plays a central role in host defense against diverse pathogens. It is produced by activated T-cells and certain cell types of innate immune system. The active protein functions as either a homodimer with other interleukin-17 family members and signals through the interleukin-17 receptor to induce inflammatory cytokine production. Aberrant expression of this gene is associated with autoinflammatory diseases including rheumatoid arthritis,psoriasis and multiple sclerosis.