Human neutrophils produce macrophage inhibitory protein-1 beta but not type 1 interferons in response to viral stimulation

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 cyto kine production. However, neutrophils seem to have a limited capacity for c ytokine production but possess efficient defense mechanisms vs. bacterial i nfection by phagocytosis and degranulation, To determine whether they also have antiviral functions, IFN-alpha and IFN-beta were measured in preparati ons of pure neutrophils, The capacity of neutrophils to produce type I IFN is controversial. Additionally, macrophage inflammatory protein-1 alpha (MI P-1 alpha) and MIP-1 beta were measured, as they are described to have indi rect or direct antiviral activity. As stimulants, active and inactivated Ne wcastle disease virus (NDV), Sendai virus, and granulocyte colony-stimulati ng factor (G-CSF) were used, Peripheral blood mononuclear cells (PBMC) from the same donors were highly reactive to viral stimulation, whereas neutrop hils failed to produce IFN but produced MIP-1 beta in response to NDV. We c onclude that neutrophils fail to prevent viral infection by IFN production but probably possess alternative mechanisms, such as secreting MIP-1 beta i n response to viruses.