Human IL-17F (Interleukin-17F) is a pro-inflammatory cytokine belonging to the IL-17 family that plays an important role in host defense and immune-mediated inflammation. IL-17F is produced primarily by Th17 CD4⁺ T cells, as well as by γδ T cells, innate lymphoid cells (ILC3s), and other activated lymphocyte populations in response to microbial infection and inflammatory stimuli. It signals through the IL-17 receptor complex (IL-17RA/IL-17RC) to induce expression of pro-inflammatory cytokines (such as IL-6 and TNF-α), chemokines (including CXCL8/IL-8), and antimicrobial peptides, thereby promoting neutrophil recruitment and strengthening mucosal barrier immunity, particularly in the respiratory and gastrointestinal tracts. IL-17F can act independently or synergistically with IL-17A to amplify inflammatory signaling. In healthy individuals, basal IL-17F levels are typically low, but expression increases during bacterial and fungal infections and in chronic inflammatory conditions. Dysregulated IL-17F has been implicated in psoriasis, asthma, inflammatory bowel disease, rheumatoid arthritis, and other autoimmune or inflammatory disorders. In clinical and translational research, human IL-17F is studied as a mediator of Th17-driven immune responses and neutrophilic inflammation and as a potential therapeutic target in immune-mediated inflammatory diseases.