SURFACE EXPRESSION OF CD63 ANTIGEN (AD1 ANTIGEN) IN P815 MASTOCYTOMA-CELLS BY TRANSFECTED IGE RECEPTORS

The surface expression of CD63 antigen in rat basuphilic leukemia cell s (RBL-2H3) was observed after antigen stimulation by confocal fluores cence microscopy. The surface expression of CD63 antigen reflected the degranulation in RBL-2H3 cells. Then, we did the same experiments in P815 mastocytoma cells with transfected IgE receptors. The expression was observed in P815 cells with normal IgE receptors, but not in P815 variant cells with IgE receptors which were missing a C-terminal cytop lasmic domain of beta or gamma subunit. In addition, the expression in P815 cells with normal IgE receptors was mostly blocked by the pretre atment of herbimycin A. The results suggested that tyrosine phosphoryl ation of the C-terminal cytoplasmic domains of beta and gamma subunits was essential for degranulation. (C) 1996 Academic Press, Inc.