IL-17A/F

Class

Interleukin inhibitor

Interleukin-17A (IL-17A) and interleukin-17F (IL-17F) are related signaling proteins (cytokines) produced mainly by a subset of immune cells called Th17 cells, along with other innate immune cells. Both cytokines bind the same receptor complex on skin, joint, and gut tissue cells, triggering production of inflammatory mediators and antimicrobial proteins that recruit neutrophils and other immune cells. In autoimmune and inflammatory diseases such as psoriasis, psoriatic arthritis, and ankylosing spondylitis, this axis becomes chronically overactive, driving persistent tissue inflammation, skin plaque formation, and joint damage. IL-17A has historically been the primary target of interleukin inhibitors, but IL-17F can activate the same receptor independently and contributes meaningfully to disease activity, particularly in tissues like the skin. Agents that neutralize both IL-17A and IL-17F, rather than IL-17A alone, aim to achieve broader suppression of this inflammatory pathway. This dual-inhibition approach reflects the biological rationale that blocking a single family member may leave a parallel route of receptor activation intact. Because IL-17 signaling also supports normal defense against certain fungal and bacterial infections at epithelial barriers, modulating this pathway carries an inherent trade-off between reducing pathological inflammation and preserving protective immune function.