Expression of the Alpha Chain of Human FcεRI in Transfected Rat Basophilic Leukemia Cells: Functional Activation after Sensitization with Human Mite-Specific IgE

摘要

The actual dilemma in studying the binding and triggering capacity of IgE from allergic patients is the lack of cultured basophils or mast cell analogs of human origin. Human IgE binds with exquisite species specificity to the high affinity IgE receptor (FcεRI) expressed on the surface of these cells. In rodents this receptor has been characterized as a tetrameric plasma membrane protein composed of an IgE-binding α chain, a β chain and two disulfide-linked γ chains. In order to establish a cell line expressing the α chain of human FcεRI which can be triggered with IgE from human patients and specific allergen, we transfected the cDNA coding for the human α subunit into rat basophilic leukemia cells. The resulting transfectants express the human α chain on the cell surface in the form of a hybrid complex associated with endogenous rat γ chains. After sensitization with human IgE from mite-specific patients, the transfectant produces a calcium response upon incubation with allergen. The established cell line can be used as a model system to study the mechanism of mast cell triggering through IgE from allergic