Previous studies have found that type III interferon (IFN-λ) is important for innate immune protection at mucosal surfaces and therefore may have therapeutic benefit against influenza A virus (IAV) infection. The authors were interested in the mechanisms through which IFN-λ leads to adaptive immune protection against IAV. They found that IFN-λ signalling in dendritic cell (DC) populations was critical for the development of protective IAV-specific CD8+ T cell responses. When mice lacked the IFN-λ receptor (Ifnlr1-/-), they had blunted CD8+ T cell responses relative to the wild type and experienced reduced survival following heterosubtypic IAV re-challenge. An analysis of DCs found that IFN-λ signalling directs the migration and function of CD103+ DCs for the development of optimal antiviral CD8+ T cell responses, and bioinformatic analyses was able to identify IFN-λ regulation of a DC IL-10 immunoregulatory network. Therefore IFN-λ does appear to serve a critical role in bridging innate and adaptive immunity from the lung mucosa to lymph nodes in order to programme DCs to direct effective T cell immunity against IAV.
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