Interferon lambda 3 （IFN-λ3）, also known as interleukin-28B （IL-28B）, is a type III interferon that plays a crucial role in the innate immune response against viral infections. IFN-λ3 is produced in response to viral stimuli and exerts potent antiviral effects by inducing the expression of interferon-stimulated genes （ISGs） that inhibit viral replication and spread. Similar to other type III interferons, IFN-λ3 signals through the IFN-λ receptor complex, which consists of IL-10R2 and IL-28Rα subunits, leading to the activation of downstream signaling pathways involved in antiviral defense. IFN-λ3 has been implicated in the immune response to various viral infections, including hepatitis C virus （HCV） and influenza virus, and is considered a promising therapeutic target for the treatment of viral diseases.