Human Neutrophils Produce Macrophage Inhibitory Protein-1β but Not Type I Interferons in Response to Viral Stimulation

Abstract

Several cell types have been shown to produce type I interferons (IFN). Of human leukocytes, monocytes and especially type 2 dendritic cell precursors (pDC2) seem to be the main producers and also have a wide spectrum of cytokine production. However, neutrophils seem to have a limited capacity for cytokine production but possess efficient defense mechanisms vs. bacterial infection by phagocytosis and degranulation. To determine whether they also have antiviral functions, IFN-α and IFN-β were measured in preparations of pure neutrophils. The capacity of neutrophils to produce type I IFN is controversial. Additionally, macrophage inflammatory protein-1α (MIP-1α) and MIP-1β were measured, as they are described to have indirect or direct antiviral activity. As stimulants, active and inactivated Newcastle disease virus (NDV), Sendai virus, and granulocyte colony-stimulating factor (G-CSF) were used. Peripheral blood mononuclear cells (PBMC) from the same donors were highly reactive to viral stimulation, whereas neutrophils failed to produce IFN but produced MIP-1β in response to NDV. We conclude that neutrophils fail to prevent viral infection by IFN production but probably possess alternative mechanisms, such as secreting MIP-1β in response to viruses.