MAST-CELL PHAGOCYTOSIS OF FIMH-EXPRESSING ENTEROBACTERIA

Most studies of mast cells have been directed at their role in the pat hophysiology of IgE-mediated allergic reactions with little recognitio n of their participation in bacterial infections. We report that mast cells can specifically bind FimH, a mannose-binding subunit on type 1 fimbriae expressed by Escherichia coli and other enterobacteria. This interaction triggers mast cell phagocytosis and killing of the bacteri a within acidified vacuoles and through the release of superoxide anio ns. Also, in view of the fact that mast cells have the capacity to rel ease inflammatory mediators and are particularly abundant in the skin, mucosal surfaces, and around blood vessels, we suggest that these cel ls play an important role in host defense against microbial infection.