Basophils and Mast Cells Basic Biology and Clinical Significance

Abstract

Basophils and mast cells are thought to represent critical effector cells in IgEdependent host responses to parasites and allergie diseases, and may also have important functions in a variety of other immunological, pathological, and perhaps physiological processes. Ehrlich identified mast cells in human connective tissues on the basis of the metachromatic staining properties of their prominent cytoplasmic granules (Ehrlich, 1878). Metachromasia refers to the change in color of some basic dyes that occurs when they bind to certain highly charged molecules, including some of the constituents of mast cell cytoplasmic granules. Ehrlich also described the basophil, a circulating leukocyte that contains cytoplasmic granules with staining properties similar to those of the mast cell (Ehrlich, 1879). Mast cells and basophils share several notable features besides staining properties (summarized in Table I). Both cell types are derived from bone marrow progenitor cells and both mast cells and basophils represent a major source of histamine and other potent chemical mediators which have been implicated in a wide variety of inflammatory and immunologie processes, including allergie disorders with components of immediate hypersensitivity (reviewed in Galli and Lichtenstein, 1988; Holgate et al., 1993; Metcalfe et al., 1981; Schwartz and Huff, 1993; Galli, 1990, 1993). All in all mammalian species yet analyzed, both mast cells and basophils express plasma membrane receptors (FceRI) that specifically bind, with high affinity, the Fc portion of IgE antibody (Beaven and Metzger,, 1993; Kinet, 1990; Ishizaka, 1988; Benhamou and Siraganian, 1992).