IL-17A/F is a heterodimer of IL-17A and IL-17F, two of the most studied members of the IL-17 family, consisting of at least six proinflammatory cytokines. Among the IL-17 family members, IL-17A and IL-17F share the highest sequence homology of 50%, and they are located on the same chromosome region.? Earlier studies have shown that both IL-17A and IL-17F are produced as homodimers by Th17 cells, an activated subset of CD4+ T cells.? However, recent studies demonstrate that the IL-17A/F heterodimer is also produced in Th17 cells as a 40 kD, secreted, disulfide-linked glycoprotein.Functionally, IL-17A/F heterodimers signal through the same receptor as IL-17A and IL-17F homodimers and induce similar biological responses. However, both mouse and human IL-17A demonstrate more than 100-fold higher biological activity than IL-17F, while IL- 17A/F has intermediate activity.? Both IL-17A and IL-17F have been associated with many inflammatory diseases in humans such as rheumatoid arthritis, multiple sclerosis, psoriasis, inflammatory bowel disease, and asthma. The exact cellular functions of IL-17A/F and its role in the disease processes are still not very clear. The IL-17A/F ELISA Max Set will be a very useful tool for those involved in the IL-17A, IL-17F, and IL-17A/F research efforts.Both the ELISA Max? Set Standard and ELISA Max? Set Deluxe are specifically engineered for accurate recovery and measurement of analytes in complex fluids, such as serum and plasma (as well as activated cell cultures) without any interference by confounding serum factors, such as heterophilic antibody or rheumatoid factor.