Mechanisms of action: IFN-λ binds to a specific receptor complex (consisting of the IFN-λ receptor 1 and the IL-10 receptor 2). This binding activates signaling pathways that lead to the expression of antiviral genes, improve the antiviral state of the cells and promote the immune response against viral infections.
Role in viral infections: IFN-λ is particularly important in the defense against viral infections, such as hepatitis C virus(HCV), influenza and various other RNA and DNA viruses. It helps to limit the replication and spread of viruses. Thus, extensive functions of IFN-λ in anti-enteric SARS-CoV-2 infection have also been described, implying possible application of IFN-λ as a therapeutic agent for COVID-19 with intestinal symptoms (Pan YY et al. 2023).
Tissue specificity: One of the characteristic features of IFN-λ is its tissue-specific action. It is particularly effective on epithelial cells, which are the primary site of viral infection for many pathogens. This makes it an important player in mucosal immunity. Thus, interferon λ (IFN-λ) stimulates immunomodulatory signals that act on epithelial cells and few other cell types due to restricted IFN-λ receptor expression (Wallace JW et al. 2021). IFN-λ has been shown to act via non-epithelial cell types, such as neutrophil granulocytes, to protect against excessive inflammation. In most cases, IFN-λ shows the ability to coordinate the host antiviral response without triggering collateral hyperinflammation, suggesting that IFN-λ signaling pathways may be a therapeutic target in IBD (Wallace JW et al. 2021).