Interferon system (IFN system)

The endogenous interferon system is a complex network of cytokines and receptors essential for the host's innate immune defense against viral infections and the regulation of adaptive immunity (Ivashkiv & Donlin, 2014, Nature Reviews Immunology). It is categorized into three main types: Type I (e.g., IFN-alpha, IFN-beta), Type II (IFN-gamma), and Type III (IFN-lambda), each signaling through distinct receptor complexes to activate the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway (Schindler et al., 2007, Journal of Biological Chemistry). Activation of this system leads to the expression of hundreds of interferon-stimulated genes (ISGs) that establish an antiviral state, inhibit cell proliferation, and modulate immune cell activity (Kotenko & Durbin, 2017, Nature Immunology). While crucial for pathogen clearance, chronic or excessive interferon signaling is a hallmark of autoimmune 'interferonopathies,' such as systemic lupus erythematosus (SLE) (Morand et al., 2020, New England Journal of Medicine). Pharmacological intervention includes the use of recombinant interferons as antiviral or immunomodulatory therapies, as well as the development of monoclonal antibodies and JAK inhibitors to suppress the system in inflammatory and autoimmune contexts (Kieseier, 2011, CNS Drugs).

Other names

Interferon signaling pathwayEndogenous interferon pathwayType I, II, and III interferon pathways

The system is modulated through several mechanisms: direct agonism of interferon receptors using recombinant proteins (e.g., IFN-alpha for hepatitis, IFN-beta for MS); antagonism of receptors such as IFNAR1 (e.g., anifrolumab for SLE); neutralization of specific cytokines like IFN-gamma (e.g., emapalumab for HLH); and inhibition of downstream signaling components like Janus kinases (JAK1/2) to prevent the transcription of interferon-stimulated genes.