Interleukin-29

Interleukins (from Latin/Greek inter = between; leukos = white; kinein = to move) are a group of endogenous, short-chain regulatory proteins (cytokines) of the immune system (IL1-IL38). Interleukins are mediators for induction, course and control of T-cell-mediated cytotoxic immune reactions as well as B-cell activation (antibody production). They are mainly formed and secreted by stimulated leukocytes, monocytes and macrophages. So far, about 38 different interleukins have been clearly identified. Each cytokine of the interleukin group is nomenclatically assigned a number for its classification (IL-1 to IL-38, status 2017).

Interleukin-29 (IL-29), also known as IFN gamma 1, is a 179 amino acid, non-glycosylated,19.9 kDa protein encoded by the IL29 gene located on chromosome 19 (gene locus: 19: 39.3).

IL-29, like the homologous interleukin-28, with which interleukin-29 has a high amino acid sequence agreement, is a member of the interleukin-10 family. It is a type III interferon (hence the name IFNgamma1).

IL-29 is expressed by virally infected cells, including Th1-7 cells. IL-29 therefore plays an important role in the defence against microbial and viral infections. Furthermore, the cytokine can be detected in lesional synovial macrophages and fibroblasts in patients with rheumatoid arthritis. Interleukin-29 has been shown to be expressed in psoriatic skin, but not in the skin of the neurodermatitis patient.

In rheumatoid arthritis (RA) elevated interleukin-29 levels are measured, which may show a positive correlation with rheumatoid factor, anti-CCP antibody and clinical activity.

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