Degranulation of Basophils and Mast Cells
Anaphylactic degranulation (AND) of basophils and mast cells is an example of regulated secretion in these specialized secretory cells (A. M. Dvorak, 1978, 1986b, 1988a,b, 1989a; A. M. Dvorak et al., 1983d; Galli et al., 1984). Basophils and mast cells, like secretory cells in general, store their specific secretory products in membrane-bound containers and release them by exocytosis, given an appropriate stimulus. AND is the term used to identify this process when the specific stimulus is the binding of multivalent antigen to cell-bound IgE antibody. This specific stimulus elicits the explosive release of granules and their preformed mediators. The functional end result of this secretory process is similar, regardless of cell, species, or trigger used to elicit AND. The ultrastructural morphology of this event also has many similarities, regardless of cell, species, or trigger. For these reasons, we refer to all secretory events of basophils and mast cells sharing the morphology of this exocytotic process as AND, in recognition of their basic morphologic similarities to the IgE-mediated mechanism. The common feature of AND in the basophils and mast cells we have studied is the noncytotoxic and rapid release of visible granule contents in parallel with preformed granule mediators. Specific morphologies accompanying this regulated secretory process in the several systems we have studied are described here (Table III).