IL-28 and IL-29

Human/mouse IL-28A (IFN-lambda 2), IL-28B (IFN-lambda 3), and human IL-29 (IFN-lambda 1) are class II cytokine receptor ligands that are distantly related to members of the IL-10 family (11 - 13% amino acid (aa) sequence identity) and type I IFN family (15 - 19% aa sequence identity). These cytokines exert bioactivities that overlap those of type I IFNs, including antiviral activity and up-regulation of MHC class I antigen expression. The proteins signal through the same heterodimeric receptor complex that is composed of the IL-10 receptor beta (IL-10 R beta) and a novel IL-28 receptor alpha (IL-28 R alpha, also known as IFN-lambda R1). Mouse IL-28 shares 61%, 62%, and 52% aa identity with human IL-28A, IL-28B, and IL-29, respectively.