Type Iii Interferons In Antiviral Immunity

Virus infections stimulate host immune responses characterized by production of interferons (IFNs). The identification of IFN-lambda (alternatively termed interleukin 28A/B, 29 or type III IFNs) has revealed that the immune response to viruses has more components than the type I IFNs known for more than SO years. IFN-lambda s are known to have type-I-IFN-like biological activities, but our understanding of these novel players in the antiviral response is still under development. In this chapter, we describe the current knowledge on expression and function of type III IFNs in innate antiviral immune defences and discuss recent findings proposing IFN-lambda to shape the adaptive immune response. We suggest that type III IFNs are key antiviral cytokines exerting direct antiviral functions at epithelial surfaces at the early stages of infection, and that this class of cytokines also promotes antigen-specific cytotoxic activity of CD8+ T lymphocytes at later stages of the antiviral immune response.