Interferon lambda 2 （IFN-λ2）, also known as IL-28A, is a member of the type III interferon family, which also includes IFN-λ1 and IFN-λ3. IFN-λ2 plays a crucial role in the innate immune response to viral infections and has been shown to exhibit antiviral activity against a variety of viruses, including hepatitis C virus, influenza virus, and others. It signals through the IFN-λ receptor complex, leading to the activation of JAK-STAT signaling pathways and the induction of interferon-stimulated genes （ISGs） that contribute to the antiviral defense mechanisms. IFN-λ2 is primarily produced by immune cells, such as dendritic cells and macrophages, in response to viral stimuli and functions as a key mediator of the host's defense against viral pathogens.