Interleukin 28

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Interleukin 28A
Alt. symbolsIFNL2
Other data
LocusChr. 19 q13.13
Interleukin 28B
Alt. symbolsIFNL3
Other data
LocusChr. 19 q13.13

Interleukin-28 (IL-28) is a cytokine that comes in two isoforms, IL-28A and IL-28B, and plays a role in immune defense against viruses, including the induction of an "antiviral state" by turning on Mx proteins, 2',5'-oligoadenylate synthetase as well as ISGF3G (Interferon Stimulated Gene Factor 3).[1] IL-28A and IL-28B belong to the type III interferon family of cytokines and are highly similar (in amino acid sequence) to IL-29. Their classification as Interferons is due to their ability to induce an antiviral state, while their additional classification as cytokines is due to their chromosomal location as well as the fact that they are encoded by multiple exons, as opposed to a single exon, as most type-I IFNs are.


IL-28 was discovered in 2002 by Zymogenetics[2] using a genomic screening process in which the entire human genome was scanned for putative genes. Once these genes were found, a second scan was performed to look specifically for cytokines. Both IL-28 and IL-29 were found in humans using this type of analysis.


IL-28 genes are located near IL-29 on chromosome 19 in humans. The two isoforms of IL-28 (IL-28A and IL-28B) are 96% homologous. Differences in function between the two forms remains unclear.

The receptor for IL-28 is composed of a unique IL-28 Receptor Alpha chain which pairs with the IL-10 Receptor Beta chain, leading many to classify IL-28 as an IL-10-like family member.


IL-28 has also been shown to play a role in the adaptive immune response, as its inclusion as an immunoadjuvant during small animal vaccination lead to augmented antigen-specific Interferon Gamma release as well as an increased cytotoxic potential in CD8+ T cells.[3]

Clinical significance

Addition of IL-28 to vaccination results in 100% protection from a lethal H1N1 Influenza challenge in a small animal model when it was paired with an Influenza vaccine that protected only 50% of the time without IL-28.[3]

Studies of IL-28B in non-human primate models of vaccination confirmed the small animal models, leading to an increase in Interferon Gamma production and CD8+ T cell activity in the form of cytotoxicity in an HIV vaccine study.[4] Scientists have credited this link to explain why some people infected with HSV-1 experience cold sores, while others do not.

A single nucleotide polymorphism (SNP) near the IL28B gene predicts response to hepatitis C treatment with interferon and ribavirin.[5][6] The SNP was identified in a genome-wide association study (GWAS) and is to date the best example of a successful GWAS hit that is clinically relevant.[7]


  1. Kempuraj D, Donelan J, Frydas S, Iezzi T, Conti F, Boucher W, Papadopoulou NG, Madhappan B, Letourneau L, Cao J, Sabatino G, Meneghini F, Stellin L, Verna N, Riccioni G, Theoharides TC (2004). "Interleukin-28 and 29 (IL-28 and IL-29): new cytokines with anti-viral activities". Int J Immunopathol Pharmacol. 17 (2): 103–6. PMID 15171810.
  2. Sheppard P, Kindsvogel W, Xu W, Henderson K, Schlutsmeyer S, Whitmore TE, Kuestner R, Garrigues U, Birks C, Roraback J, Ostrander C, Dong D, Shin J, Presnell S, Fox B, Haldeman B, Cooper E, Taft D, Gilbert T, Grant FJ, Tackett M, Krivan W, McKnight G, Clegg C, Foster D, Klucher KM (January 2003). "IL-28, IL-29 and their class II cytokine receptor IL-28R". Nat. Immunol. 4 (1): 63–8. doi:10.1038/ni873. PMID 12469119.
  3. 3.0 3.1 Morrow MP, Pankhong P, Laddy DJ, Schoenly KA, Yan J, Cisper N, Weiner DB (June 2009). "Comparative ability of IL-12 and IL-28B to regulate Treg populations and enhance adaptive cellular immunity". Blood. 113 (23): 5868–77. doi:10.1182/blood-2008-11-190520. PMC 2700323. PMID 19304955.
  4. Morrow MP, Yan J, Pankhong P, Shedlock DJ, Lewis MG, Talbott K, Toporovski R, Khan AS, Sardesai NY, Weiner DB (Sep 2010). "IL-28B/IFN-lambda 3 drives granzyme B loading and significantly increases CTL killing activity in macaques". Molecular Therapy. 18 (9): 1714–23. doi:10.1038/mt.2010.118. PMC 2956930. PMID 20571540.
  5. PGxNews.Org (August 2009). "New biomarker predicts response to hepatitis C treatment". PGxNews.Org. Archived from the original on November 21, 2009. Retrieved 2009-08-17.
  6. Ge D; Fellay j; Thompson A; et al. (2009). "Genetic variation in IL28B predicts hepatitis C treatment-induced viral clearance". Nature. 461 (7262): 399–401. doi:10.1038/nature08309. PMID 19684573.
  7. Maxmen, Amy. "Pharmacogenomics: Playing the odds". Nature. 474 (7350): S9–S10. doi:10.1038/474S9a. PMID 21666735.