The mast cell and gut nematodes: damage and defence.

Gut nematode infection induces a dominant type 2 immune response, crypt hyperplasia and mucosal mastocytosis. Despite their strong association with nematode infection, the role of mast cells in the mechanism of worm expulsion is yet to be fully defined. Recent work suggests that they contribute to resistance, aiding the effector mechanisms which ultimately result in worm expulsion. Although it is widely accepted that both connective and mucosal mast cells arise from a common progenitor, it is clear that mucosal mastocytosis is dependent on the presence of type 2 cytokines such as interleukin 4 (IL-4), IL-9, IL-10 and IL-13. Importantly, it is now evident that mucosal mast cells can amplify this protective response, as well as contributing to intestinal pathology. Here we discuss current areas of interest in this field, including the potentially conflicting role that mast cells play in intestinal inflammation. We also highlight the significance of these responses to current ideas relating to parasite infection and allergy.