ABSTRACT
In mast cells and basophils, the crosslinking of cell surface IgE receptors is the first of a series of events leading to the release of inflammatory mediators and vasoactive amines from granules. One of the best characterized is RBL-2H3, a line of rat leukemia cells that provides an in vitro model for the study of mucosal mast cells. RBL-2H3 cells are a cultured line developed by Metzger, Siraganian and colleagues from basophil-like solid tumor that occurred in a ß-chloroethylamine-treated rat. The IgE receptor-mediated activation of RBL-2H3 cells can occur either directly or in a two-step reaction. One missing element in the analysis of signal transduction in RBL-2H3 cells has been insight into the molecular mechanisms that couple crosslinked IgE receptors to transducer and effector proteins. The chapter proposes that crosslinked IgE receptors can exist in two states at the RBL-2H3 cell surface, one that is competent to trigger secretion and one that is either inactive or directly inhibitory to secretion.
