[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Immunology](https://durgical.com/en/immunology/) › [Cytokines and molecules](https://durgical.com/en/immunology/#a-molecules) › Interleukin-17 [Immunology](https://durgical.com/en/immunology/) · [Cytokines and molecules](https://durgical.com/en/immunology/#a-molecules) # Interleukin-17 - Molecule IL-17 calls neutrophils to skin and mucosa and protects against Candida; too much of it drives psoriasis. Updated 2026-11-01 **See it in 3D:** [Skin](https://durgical.com/en/anatomy/skin/) ## Key points - Th17 differentiation: TGF-β + IL-6 (+ IL-21); IL-23 maintains them; master factor RORγt. - Effect: neutrophil recruitment and antimicrobial peptides (β-defensins) at barriers. - Inborn IL-17 or IL-17 receptor defects cause chronic mucocutaneous candidiasis. - Psoriasis, psoriatic arthritis, ankylosing spondylitis: secukinumab, ixekizumab (IL-17A), bimekizumab (IL-17A and F), brodalumab (receptor). - IL-17 blockers can cause Candida infections and may flare or unmask inflammatory bowel disease. ## What it is IL-17 is a family of six cytokines; IL-17A and IL-17F are the most important in disease. They are made by Th17 cells and also by γδ T cells, MAIT cells and group 3 innate lymphoid cells. IL-17 acts on epithelial cells and keratinocytes, which then release chemokines (IL-8, CCL20) and antimicrobial peptides, bringing neutrophils and more Th17 cells to the site. ## Function - Defence of skin and mucosa against fungi (especially Candida) and extracellular bacteria. - Induces keratinocytes to make chemokines and antimicrobial peptides. - Its receptor is a heterodimer that includes IL-17RA and is widely expressed on epithelial cells. ## Clinical notes - Psoriasis: the IL-23/IL-17 axis is the central driver of plaques; IL-17A blockade acts quickly. - Axial spondyloarthritis and psoriatic arthritis respond to IL-17 blockade; hidradenitis suppurativa is another approved use of secukinumab. - Unlike anti-TNF and anti-IL-12/23 drugs, anti-IL-17 agents did not help Crohn disease and some patients worsened, suggesting IL-17 protects the gut lining. - Before treatment latent tuberculosis is screened for, as with other biologics. ## Memory aid Seventeen guards the doors (skin and mucosa): when it is missing Candida walks in, when it is excessive the skin builds plaques. ## Test yourself Think of the answer, then tap the question to see it. ## Which infection points to a defect in IL-17 immunity? Chronic mucocutaneous candidiasis, recurrent Candida of skin, nails and mucosa. ## Why are IL-17 blockers avoided in active Crohn disease? Trials showed no benefit and some flares; IL-17 seems to help protect the intestinal barrier. ## What do keratinocytes release under IL-17 stimulation? Chemokines such as IL-8 and CCL20 and antimicrobial peptides such as β-defensin 2, which bring in neutrophils and Th17 cells. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/immunology/interleukin-17/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Skin](https://durgical.com/en/anatomy/skin/) ## Related - [Cytokines: the table to know](https://durgical.com/en/immunology/cytokines-the-table-to-know/) - [IL-12 and IL-23](https://durgical.com/en/immunology/il-12-and-il-23/) - [IL-8 and the chemokines](https://durgical.com/en/immunology/il-8-and-the-chemokines/) - [Interleukin-6](https://durgical.com/en/immunology/interleukin-6/) - [IL-10 and TGF-β (the brakes)](https://durgical.com/en/immunology/il-10-and-tgf/) - [Th1, Th2, Th17, Tfh and Treg](https://durgical.com/en/immunology/th1-th2-th17-tfh-and-treg/) - [Neutrophil](https://durgical.com/en/immunology/neutrophil/) - [T-cell and combined deficiencies: DiGeorge, SCID, Wiskott–Aldrich, ataxia-telangiectasia](https://durgical.com/en/immunology/t-cell-and-combined-deficiencies-digeorge-scid-wiskott-aldrich-ataxia-telangiect/) ## Related conditions - [Ankylosing spondylitis](https://durgical.com/en/conditions/ankylosing-spondylitis/) - [Crohn disease](https://durgical.com/en/conditions/crohn-disease/) ## Microorganisms - [Candida albicans](https://durgical.com/en/microbiology/candida-albicans/) ## In Pharmacology - [Secukinumab](https://durgical.com/en/pharmacology/secukinumab/) [← All of immunology](https://durgical.com/en/immunology/) Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given. Sources: [Major Role of the IL17/23 Axis in Psoriasis Supports the Development of New Targeted Therapies](https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.621956/full) (Frontiers in Immunology, 2021); [Secukinumab Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a615011.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [Pro-Inflammatory and Anti-Inflammatory Interleukins in Infectious Diseases: A Comprehensive Review](https://pmc.ncbi.nlm.nih.gov/articles/PMC10818686/) (Tropical Medicine and Infectious Disease (PubMed Central), 2024); [Th17/Treg imbalance in inflammatory bowel disease: immunological mechanisms and microbiota-driven regulation](https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1651063/full) (Frontiers in Immunology, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/immunology/interleukin-17/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/immunology/interleukin-17/