The Paul Kallos Memorial Lecture. The mast cell: a versatile effector cell for a challenging world.

Mast cells are phenotypically and functionally versatile effector cells. When activated by IgE-dependent or other mechanisms, mast cells can produce a diverse array of mediators including TNF-alpha and many other cytokines. Moreover, mast cells can express increased numbers of high-affinity surface receptors for IgE (Fc epsilonRI) and enhanced levels of IgE-dependent mediator secretion in response to elevations in concentrations of IgE. These characteristics (and others) have suggested diverse potential roles for mast cells in health and disease. To test specific hypotheses about mast cell function in allergic reactions and other biological responses in vivo, one can employ genetically mast-cell-deficient Kit(W)/Kit(W-v) mice which do or do not contain adoptively transferred mast cell populations derived from genetically compatible wild-type mice or mice with mutations that influence mast cell biology. Such work has already indicated that mast cells (and, in some cases, mast-cell-derived cytokines) can have a critical role in the expression of the acute, late-phase and chronic components of IgE-dependent allergic inflammation and can influence the development of an important functional consequence of such reactions: airways hyperresponsiveness. However, mast cells can also perform important beneficial roles in host defense, both in IgE-dependent immune responses to certain parasites and in natural immunity to bacterial infection.