The IL28B gene encodes a cytokine distantly related to type I interferons and the IL-10 family. IL28B, IL28A, and IL29 are three closely related cytokine genes that form a cytokine gene cluster on a chromosomal region mapped to 19q13. Expression of the cytokines encoded by the three genes can be induced by viral infection. All three cytokines have been shown to interact with a heterodimeric class II cytokine receptor that consists of interleukin 10 receptor, beta (IL10RB) and interleukin 28 receptor, alpha (IL28RA).Synonyms: IFN-lambda-3, Ifnl3, Il28, Il28b, Interferon lambda-3