Interleukin 29

Interleukin 29 (IL-29) belongs to a group of structurally and functionally related cytokines (classified as type III interferons) comprising the proteins IL-28A, IL-28B and IL-29. The cytokines are also known as Interferon (IFN)-λ2, IFN-λ3 en IFN-λ1, respectively, and are part of a larger family of structurally related cytokines called the IL-10-IFN family. This family includes IL-10, IL-19, IL-20, IL-22, IL-24, IL-26, IL-28A, IL-28B, IL-29, type 1 IFNs (IFN-α, IFN-β, IFN-κ, IFN-δ, IFN-ε, IFN-τ, IFN-ω, and IFN-ζ) and type II IFN (IFN-γ).

Figure This is a structure of IL-29 created using the data from Protein Data Bank (PDB: 3OG4) and rendered using PyMOL.

The mature polypeptides of IL-28A/IL-28B and IL-29 contain 175 and 181 amino acids, respectively. The amino acid sequences between human IL-29 and IL-28 is similar for approximately 81%, whereas IL-28A and IL-28B are almost identical (96%). Regarding the other IL-10-IFN family members, IL-28A/B shows the highest amino acid homology with IFN-α (22%), IFN-ω (21%), and IL-24 (19%). IL-29, however, shows the highest sequence similarity toward IL-20 (19%) and IL-26 (16%).

After viral infection the production of not only type 1 IFNs is stimulated but also that of IL-28 and IL-29. Both cytokines were shown to reduce viral replication of a range of viruses, including DNA viruses and single-stranded RNA viruses. In spite of functional similarities between IFN-α/β and IL-29, the latter does not bind to the IFN-α/β receptor, but instead signals through a receptor composed of the IL-28R1 and IL-10R2 subunits. In addition, the receptor for IFN-α/β is expressed on nearly all somatic cells, whereas the receptor for IL-29 is primarily expressed on nonhematopoietic cells and less on leukocytes. IL-28 and IL-29 also possess antigrowth activity, which, however, seems to be more limited than that of type I IFNs.

Detecting IL-29 with U-CyTech products

ELISA products

Human IL-29 ELISA