The interleukin-17 (IL-17) family comprises IL-17A, IL-17B, IL-17C, IL-17D, IL-17E, and IL-17F. Interleukin 17A is a pro-inflammatory cytokine and its overexpression follows an invasion of the body by pathogens. Promoting the inflammation, IL-17 acts in concert with tumor necrosis factor and interleukin-1. Moreover, activation of IL-17 signaling is often observed in the pathogenesis of various autoimmune disorders, such as psoriasis. The BioVendor immunoassays are validated for the measurement of specific members of the protein family in serum, plasma or cell culture medium.