IRF8 also named as ICSBP1, is a transcription factor of the IFN regulatory factor (IRF) family. The IRF family proteins bind to the IFN-stimulated response element (ISRE) and regulate expression of genes stimulated by type I IFNs, namely IFN-alpha and IFN-beta. IRF family proteins also control expression of IFN-alpha and IFN-beta-regulated genes that are induced by viral infection. IRF8 specifically binds to the upstream regulatory region of type I IFN and IFN-inducible MHC class I genes (the IFN consensus sequence (ICS)). It plays a negative regulatory role in cells of the immune system. It is predominantly in lymphoid tissues.