Licensing Delineates Helper and Effector NK Cell Subsets During Viral Infection

Natural killer (NK) cells can be divided into phenotypic subsets based on the expression of receptors that bind self-MHC-I molecules with differing affinities; a concept termed licensing or education. Here we show that NK cell subsets exhibit markedly different migratory, effector, and immunoregulatory functions on dendritic cells and antigen-specific CD8+ T cell responses during influenza and murine cytomegalovirus infections. Shortly after infection, unlicensed NK cells preferentially trafficked to draining lymph nodes and produced GM-CSF, which promoted the expansion and activation of dendritic cells, and ultimately resulted in sustained antigen-specific CD8+ T cell responses. In contrast, licensed NK cells preferentially migrated to infected parenchymal tissues and produced greater levels of interferon- (IFN-). Importantly, human NK cell subsets exhibited similar phenotypic characteristics and patterns of cytokine production. Collectively, our studies demonstrate a critical demarcation between the functions of licensed and unlicensed NK cell subsets, with the former functioning as the classical effector subset in inflamed tissues and the latter as modulators of adaptive immunity helping to prime immune responses in draining lymph nodes.

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Zamora AE, Aguilar EG, Sungur CM, Khuat LT, Dunai C, Lochhead GR, Du J, Pomeroy C, Blazar BR, Longo DL, Venstrom JM, Baumgarth N, Murphy WJ