Full name: Interleukin-17A

Aliases:1 IL17, CTLA8, IL-17, CTLA-8, and IL-17A

Size:2 35 kDa

Family:3 IL-17 family (IL-17A, IL-17B, IL-17C, IL-17D, IL-17E, and IL-17F)

Receptors:2 IL-17RA (= IL-17R)

Major cellular sources:2 Activated Th17 cells, CD8+ T cells, γ𝛿 T cells, NK cells, NKT cells, neutrophils, and ILCs

Major cellular targets:2,3 Epithelial/endothelial cells, fibroblasts, osteoblasts, monocytes, macrophages, B cells, T cells, myelomonocytic cells and marrow stromal cells, and chondrocytes

Disease states associated with:2 Rheumatoid arthritis, multiple sclerosis, psoriasis, inflammatory bowel disease, allergic asthma, atopic dermatitis, contact hypersensitivity, and graft-versus-host-disease

Major physiologic functions:

  • IL-17A acts mainly on non-hematopoietic cells, particularly epithelial cells, and plays an active role in maintaining immunity at boundary tissues.3

  • IL-17A acts on a variety of cells, which respond by upregulating the expression of pro-inflammatory cytokines, chemokines, metalloproteases, antimicrobial peptides, and remodeling proteins.1-3

  • By inducing cells to produce chemokines, IL-17A attracts neutrophils to mediate defense against different pathogens.2

  • IL-17A directly contributes to leukocyte migration and tissue remodeling by promoting the secretion of metalloproteases.3

  • IL-17A also regulates the activities of NF-κB and mitogen-activated protein kinases and can stimulate the expression of IL-6 and cyclooxygenase-2 (PTGS2/COX-2), as well as enhance the production of nitric oxide.1

CD: cluster of differentiation; CTLA: cytotoxic T-lymphocyte associated antigen; IL: interleukin; IL-17R: IL-17 receptor; ILC: innate lymphoid cell; NK: natural killer; NF-κB: nuclear factor-kappa B; NKT: natural killer T; Th: T helper.


  • 1.

    NCBI. Gene. IL17A interleukin 17A [Homo sapiens (human)]. Accessed March 11, 2021.

  • 2.

    Akdis M, Aab A, Altunbulakli C, et al. J Allergy Clin Immunol. 2016;138:984-1010.

  • 3.

    Brembilla NC, Senra L, Boehncke W-H. Front Immunol. 2018;9:1682.