LAG3 is a Central Regulator of NK Cell Cytokine Production

Natural killer (NK) cells are innate effectors, which play a crucial role in controlling viral infections. Administration of IFN-α has shown promising results as a therapeutic, controlling HIV, and chronic viral hepatitis. However the downstream mechanisms by which IFN-α mediates its anti-viral effects is largely unknown. In this investigation, we evaluated the impact of IFN-α on peripheral blood NK cells from healthy donors. High dimensional flow cytometry analysis of NK cell surface receptors following exposure to IFN-α showed an increased expression of the check point inhibitor LAG3. Further characterization revealed that LAG3 was expressed in a subset of NK cells with high expression of activation and maturation markers. Assessment of metabolic pathways showed that LAG3+ NK cells had enhanced rates of glycolysis and glycolytic capacity, suggesting that it is a primed effector subset with enhanced glucose metabolism. Inhibition of LAG3 on NK cells using antibody in vitro resulted in a profound increase in secretion of cytokines IFN-γ, TNF-α, MIP-1α and MIP-1β, without affecting the cytotoxic activity. Taken together, these results showed that LAG3 is a negative regulator of cytokine production by mature NK cells.