Background：This gene encodes a cytokine distantly related to type I interferons and the IL-10 family. This gene, interleukin 28A （IL28A）, and interleukin 28B （IL28B） 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）.
