Mast cells and basophils in innate immunity.

Mast cells and basophils are primarily associated with the pathophysiology of allergic diseases. Considering that these cells have been preserved through evolution they must serve a valuable function. Intrinsically, mast cells are ideally placed and well endowed with inflammatory mediators to play a critical role in immune surveillance. Recent studies have shown that mast cells and basophils can bind various bacteria even in the absence of opsonizing antibodies. The resulting interaction caused release of a variety of inflammatory mediators and, in the case of mast cells, also uptake of bacteria. Among the mediators released by these inflammatory cells, TNF-alpha appears critical as it potentiates the early neutrophil responses to bacteria. Observations in mutant mice that are deficient in mast cells has provided further evidence for the specific role of mast cells in host defense against bacteria. We believe that there is now sufficient evidence (at least for mast cells) to propose a multi-faceted and significant role for these cells in the host's innate immune response to infectious agents.