Fig. 7.

Mast cells as sentinels in virus infections. Resident mature mast cells located close to blood vessels and epithelial barriers can recognize invading viruses and initiate innate immunity by recruitment and activation of NK cells through the production of CXCL8 and type I IFNs, respectively. Additional resident cells, such as fibroblasts, can also contribute to NK cell recruitment. At mucosal surfaces, the ability of mast cells, compared to structural cells, to express a wide range of IFNs-α (1–21) in addition to chemokines, may contribute to a more diverse cell infiltrate and more sustained IFN response, and therefore influence overall antiviral immunity. In addition to these mediators, mast cells can be considered as an important source of type III IFNs (IFN-λ), which have been reported to specifically protect epithelial surfaces more effectively than type I IFNs.