Neutrophil in viral infections, friend or foe?

Abstract

Polymorphonuclear leukocytes or neutrophils are the first immune cells to the site of injury and microbial infection. Neutrophils are crucial players in controlling bacterial and fungal infections, and in particular secondary infections, by phagocytosis, degranulation and neutrophil extracellular traps (NETs). While neutrophils have been shown to play important roles in viral pathogenesis, there is a lack of detailed investigation. In this article, we will review recent progresses toward understanding the role of neutrophils in viral pathogenesis.

Figure 1. Immunostaining of NETs

(green, neutrophil elastase; red, histone-DNA complex), (a) Unstimulated neutrophils (no NETs). NETs formed after neutrophils stimulated with S. aureus (b, blue), PMA (c) and glucose oxidase (d). Bars, 10 urn. © 2007 Rockefeller University Press. Originally published in Journal of Cell Biology. Vol 176. doi: 10.1083/jcb.200606027

Figure 2. Neutrophils may be a reservoir for H5N1 and WNV

(a) Q-PCR results of WNV-infected human monocyte-derived macrophages and neutrophils at 8 h, suggesting neutrophils may act as a reservoir for WNV, **** denotes p < 0.0001, adapted from Bai et al, 2010. (b) H5N1 antigen (purple-blue; black arrows) is detected in CD15-positive cells (a neutrophil marker, red-brown; black arrows) in placental villi (inset a). Inset b shows enlargement of inset a, which shows that neutrophils contain H5N1 nucleotide sequences (bar, 10 urn), adapted from Zhao, et al., 2008. © Oxford Journals Oxford University Press.