Cutting Edge: Developmental Regulation of IFN-γ Production by Mouse Neutrophil Precursor Cells

Neutrophils are an emerging cellular source of IFN-gamma, a key cytokine that mediates host defense to intracellular pathogens. Production of IFN-gamma by neutrophils, in contrast to lymphoid cells, is TLR- and IL-12-independent and the events associated with IFN-gamma production by neutrophils are not understood. In this study, we show that mouse neutrophils express IFN-gamma during their lineage development in the bone marrow niche at the promyelocyte stage independently of microbes. IFN-gamma accumulates in primary neutrophilic granules and is released upon induction of degranulation. The developmental mechanism of IFN-gamma production in neutrophils arms the innate immune cells prior to infection and assures the potential for rapid release of IFN-gamma upon neutrophil activation, the first step during responses to many microbial infections.