Interferons

Interferons are immune cytokines that are classified, as type I, II, or III, according to the receptors through which they signal. Interferon (INF) family receptors have conserved cysteine residues and include the receptors for IFN-α, IFN-β, and IFN-γ.

 Fc receptors  Immune Cytokines  Immunoglobulins

Type	Receptor	Secreting cell / action
IFN type I IFN-α (1, 2, 4, 5, 6, 7, 8, 10, a3, 14, 16, 17, 21), IFN-β (1, 3), IFN-κ, IFN-δ, IFN-ε, IFN-τ, IFN-ω (with pseudogenes), IFN-ζ (limitin)	IFN-α receptor (IFNAR) IFNAR1 and IFNAR2 chains	plasmacytoid dendritic cells (pDCs) are the most potent producers of type I IFNs, but virtually all cells are capable of production of type I IFNs – lymphocytes (NK cells, B cells, T cells), macrophages, fibroblasts, endothelial cells, osteoblasts IFN-β is expressed primarily in nonimmune cells, and and IFN-α primarily in leukocytes
IFN type II single isotype IFN-γ	IFN-γ receptor (IFNGR) IFNGR1 and IFNGR2	activated T cells, Th1 cells, and natural killer cells. potentiates the effects of the type I IFNs, stimulates macrophages to kill engulfed bacteria, regulates Th2 response, regulation of immune response (IFN-γ production can lead to autoimmune disorders)
IFN type III types IFN-λ1(IL29), IFN-λ2 (IL28A), IFN-λ3 (IL28B) (originally called macrophage-activating factor)	IL10R2 (CRF2-4) plus IFNLR1 (CRF2-12)	IFN-λs induced by both type I and type III IFNs (belong to IFN-stimulated genes (ISGs)) induced after stimulation by viruses and display antiviral activity IFN-λs are produced by plasmacytoid dendritic cells to a greater extent than by myeloid dendritic cells
specific interferons	actions
IFN-β1a (Avonex, Rebif)	employed in treatment of multiple sclerosis (MS, DS)
IFN-β1b (Betaseron)	employed in treatment of multiple sclerosis (MS, DS)