IL-29 is encoded by the IFNL1gene located on
chromosome 19 in humans.[3][5] It is a
pseudogene in mice meaning the IL-29 protein is not produced in them.[3]
Structure
IL-29 is, with the rest of IFN-λ, structurally related to the
IL-10 family, but its primary
amino acid sequence (and also function) is more similar to type I interferons.[3] It binds to a
heterodimericreceptor composed of one
subunitIFNL1R specific for IFN-λ and a second subunit
IL10RB shared among the IL-10 family cytokines.[3]
IL-29 expression is dominant in virus-infected epithelial cells of the
respiratory,
gastrointestinal and
urogenital tracts, also in other
mucosal tissues and
skin. Hepatocytes infected by
HCV or
HBV viruses stimulate the immune response by producing IL-29 (IFN-λ in general) rather than type I interferons.[3][4] It is also produced by maturing macrophages, dendritic cells or mastocytes.[4]
It plays a role in defense against
pathogens apart from viruses.[3] It affects the function of both
innate and
adaptive immune system. Besides described antiviral effects, IL-29 modulates cytokine production of other cells, for example, it increases secretion of
IL-6,
IL-8 and
IL-10 by
monocytes and
macrophages, enhances the responsiveness of macrophages to
IFN-γ by increased expression of
IFNGR1, stimulates
T cell polarization towards
Th1 phenotype and also
B cell response to IL-29 was reported.[6]
Antitumor immunity
The impact of IL-29 on
cancer cells is complicated depending on cancer cell type. It shows protective tumor inhibiting effects in many cases such as
skin,
lung,
colorectal or
hepatocellular cancer, but shows tumor promoting effects on
multiple myeloma cells.[4] IFN-λ have potential as
cancer therapy, with effects on more restricted cell types and fewer side-effects than type I interferons.[3][4]
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