Human IRF8 Synthetic Peptide. IRF8 (interferon regulatory factor 8) is a transcriptional activator or repressor. It specifically binds to the upstream regulatory region of type I IFN and IFN-inducible MHC class I genes. IRF8 plays a negative regulatory role in cells of the immune system. It is involved in CD8+ dendritic cell differentiation by forming a complex with the BATF-JUNB heterodimer in immune cells. This leads to recognition of AICE sequence, an immune-specific regulatory element, followed by cooperative binding of BATF and IRF8 and activation of the genes. Mutations in the gene can result in immunodeficiencey 32A and 32B.