Interferon-λ orchestrates innate and adaptive mucosal immune responses

Type III interferon (IFN-lambda) was initially thought to have functions similar to those of the type I interferons (IFN-alpha and IFN-beta). New findings have indicated, however, that IFN-lambda has a non-redundant role in the innate antiviral, antifungal and antiprotozoal defences of mucosal barriers. In this Review, we highlight recent work showing that IFN-lambda inhibits virus dissemination within the body and limits the transmission of respiratory and gastrointestinal viruses to naive hosts. We also discuss findings indicating that IFN-lambda can act on neutrophils to prevent invasive pulmonary aspergillosis. We summarize results showing that IFN-lambda signalling differs in several respects from IFN-alpha and IFN-beta signalling, particularly in neutrophils. Finally, we discuss new findings indicating that IFN-lambda is a potent enhancer of adaptive immune responses in the respiratory mucosa.