[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Immunology](https://durgical.com/en/immunology/) › [Cytokines and molecules](https://durgical.com/en/immunology/#a-molecules) › Type I interferons (α, β) [Immunology](https://durgical.com/en/immunology/) · [Cytokines and molecules](https://durgical.com/en/immunology/#a-molecules) # Type I interferons (α, β) - Molecule Type I interferons are an early antiviral warning: an infected cell releases them so its neighbours resist the virus. In lupus they are overactive. Updated 2026-11-01 ## Key points - Receptor IFNAR1/IFNAR2 → JAK1 + TYK2 → ISGF3 (STAT1/STAT2/IRF9) → interferon-stimulated genes. - Antiviral state: PKR stops protein synthesis; OAS/RNase L degrades viral RNA. - Raise MHC class I and activate NK cells. - Plasmacytoid dendritic cells are the major producers; lupus shows a high interferon signature. - Anifrolumab blocks IFNAR1 (lupus); IFN-β is used in multiple sclerosis. - Typical side effect of interferon therapy: flu-like symptoms (fever, chills, myalgia). ## What it is Type I interferons include about 13 IFN-α subtypes, IFN-β and several minor members. Infected cells release them after sensing viral nucleic acids through pattern-recognition receptors, and plasmacytoid dendritic cells produce very large amounts. All of them use one receptor (IFNAR1/IFNAR2), which activates JAK1 and TYK2, forms the ISGF3 complex (STAT1, STAT2, IRF9) and switches on hundreds of interferon-stimulated genes that block viral replication. ## Step by step - A virus infects a cell; sensors detect its RNA or DNA. - The cell (or a nearby plasmacytoid dendritic cell) releases IFN-α and IFN-β. - The interferons bind IFNAR on neighbouring cells, activating JAK1 and TYK2. - ISGF3 enters the nucleus and switches on interferon-stimulated genes. - Neighbouring cells become resistant to the virus, raise MHC class I and alert NK cells. ## Clinical notes - Systemic lupus erythematosus: immune complexes containing nucleic acids stimulate plasmacytoid dendritic cells; anifrolumab is an anti-IFNAR1 antibody. - Multiple sclerosis: IFN-β reduces relapses (it does not cure the disease). - Pegylated IFN-α was a backbone of hepatitis C therapy before direct-acting antivirals and is still used in some hepatitis B cases. - Type I interferonopathies: inherited excess of interferon signalling with inflammation from infancy. - In some bacterial infections, including tuberculosis, excess type I interferon harms the host. ## Memory aid Alpha and beta are the neighbourhood siren: the infected house falls, but the whole street locks its doors. ## Test yourself Think of the answer, then tap the question to see it. ## Which receptor do all type I interferons use? IFNAR, made of IFNAR1 and IFNAR2, which signals through JAK1 and TYK2. ## Which cell is the main producer of IFN-α in lupus? The plasmacytoid dendritic cell, stimulated by nucleic acid-containing immune complexes. ## What is anifrolumab and how does it act? A human monoclonal antibody against IFNAR1; it blocks the signalling of all type I interferons in lupus. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/immunology/type-i-interferons/) ## Related - [Cytokines: the table to know](https://durgical.com/en/immunology/cytokines-the-table-to-know/) - [Interferon-γ](https://durgical.com/en/immunology/interferon/) - [Fc receptors, BCR and TCR](https://durgical.com/en/immunology/fc-receptors-bcr-and-tcr/) - [Dendritic cell (professional antigen-presenting cell)](https://durgical.com/en/immunology/dendritic-cell/) - [Natural killer cell](https://durgical.com/en/immunology/natural-killer-cell/) - [Pattern recognition: PAMPs, DAMPs, Toll-like receptors](https://durgical.com/en/immunology/pattern-recognition-pamps-damps-toll-like-receptors/) - [Autoantibodies: the table to know](https://durgical.com/en/immunology/autoantibodies-the-table-to-know/) ## Related conditions - [Systemic lupus erythematosus](https://durgical.com/en/conditions/systemic-lupus-erythematosus/) - [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/) - [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/) ## Microorganisms - [Hepatitis B virus](https://durgical.com/en/microbiology/hepatitis-b-virus/) - [Hepatitis C virus](https://durgical.com/en/microbiology/hepatitis-c-virus/) - [Influenza virus](https://durgical.com/en/microbiology/influenza-virus/) ## In Pharmacology - [Interferon beta](https://durgical.com/en/pharmacology/interferon-beta/) [← All of immunology](https://durgical.com/en/immunology/) Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given. Sources: [The Dual Nature of Type I and Type II Interferons](https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2018.02061/full) (Frontiers in Immunology, 2018); [What's New in the Treatment of Systemic Lupus Erythematosus](https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.655100/full) (Frontiers in Medicine, 2021); [Interferon Beta-1a Subcutaneous Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a604005.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [21.2 Barrier Defenses and the Innate Immune Response - Anatomy and Physiology 2e | OpenStax](https://openstax.org/books/anatomy-and-physiology-2e/pages/21-2-barrier-defenses-and-the-innate-immune-response) (OpenStax, 2022). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/immunology/type-i-interferons/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/immunology/type-i-interferons/