IFNstimulated

IFNstimulated refers to cells, genes, or responses that are activated by interferon signaling. Interferons (IFNs) are cytokines produced by host cells in response to viral infection, oncogenic stress, or other danger signals. They act by binding to cell-surface receptors: type I (IFN-α/β), type II (IFN-γ), and type III (IFN-λ). Receptor engagement activates the JAK-STAT pathway, culminating in the formation of transcription factor complexes such as ISGF3 (STAT1/STAT2/IRF9) that induce expression of a broad set of interferon-stimulated genes (ISGs). The set of ISGs constitutes the antiviral state, inhibiting viral replication and modulating immune responses.

IFNstimulated responses include antiviral effector proteins, such as MX proteins, 2'-5'-oligoadenylate synthetases (OAS) leading to RNase L activation, PKR (EIF2AK2) that inhibits translation, and IFIT family proteins that restrict viral RNA. ISGs also influence antigen presentation, cytokine production, and apoptosis.

Clinical and research relevance: Interferons are used therapeutically to treat hepatitis C (historically), certain cancers, and other viral infections; however, therapeutic use is limited by side effects and variable efficacy. In research, measuring ISG expression serves as a readout of IFN activity and innate immune status. The term "IFN-stimulated" is commonly used to describe cells or genes upregulated in response to IFN signaling, distinguishing them from basal states.