IFN-λ-mediated IL-12 production in macrophages induces IFN-γ production in human NK cells

With increasing interest in alternative options to interferon-alpha-based treatments, IFN- has shown therapeutic promise in a variety of diseases. Although the antiviral activity of IFN- has been extensively studied, there is limited knowledge regarding the immunological functions of IFN- and how these differ from those of other classes of IFNs. In this study, we investigated the effects of IFN- on primary human NK cells, both in a direct and indirect capacity. We demonstrate that in contrast to interferon-alpha, IFN- is unable to directly stimulate NK cells, due to the absence of IFN- receptor chain 1 (IFN-R1) on NK cells. However, IFN-, in combination with TLR4 challenge, is able to induce the production of select members of the IL-12 family of cytokines in monocyte-derived macrophages. We further show that through macrophage-mediated IL-12 production, IFN- is able to indirectly affect NK cells and ultimately induce IFN- production.