Differences between Type I, Type II, and Type III Interferons Type I Interferon • Source of stimulation = Bacterial and viral components • Source of production = Every cell in body e.g. leukocytes, endothelial cells, fibroblasts • Types = IFNA1, IFNA2, IFNA4, IFNA5, IFNA6, IFNA7, IFNA8, IFNA10, IFNA13, IFNA14, IFNA16, IFNA17, IFNA21. • Receptor = IFNAR-1, IFNAR-2, STAT-1, STAT-2, JAK-1, JAK-2 Type II Interferon • Source of stimulation = IL-2, IL-12 • Source of production = T cells (specially CD4+ T cells) • Types = IFN-γ (gamma) • Receptor = IFNGR, IFNGR2, STAT-1, JAK-1, JAK-2 Type III Interferons • Source of stimulation = Viral components • Source of production = Epithelial cells • Types = IFN-λ1 (IL-29), IFN-λ2 (IL-28A), IFN-λ3 (IL-28B), and IFN-λ4 • Receptor = ISGF3, STAT-1, STAT-2