MABF2317-100UG Sigma-AldrichAnti-CD23 Antibody, clone EBVCS1

IgE-mediated allergic inflammation occurs when allergens cross-link IgE on the surface of immune cells, thereby triggering the release of inflammatory mediators as well as enhancing Ag presentations. IgE is frequently present in airway secretions, and its level can be enhanced in human patients with allergic rhinitis and bronchial asthma. However, it remains completely unknown how IgE appears in the airway secretions. In this study, we show that CD23 (FcεRII) is constitutively expressed in established or primary human airway epithelial cells, and its expression is significantly upregulated when airway epithelial cells were subjected to IL-4 stimulation. In a transcytosis assay, human IgE or IgE-derived immune complex (IC) was transported across a polarized Calu-3 monolayer. Exposure of the Calu-3 monolayer to IL-4 stimulation also enhanced the transcytosis of either human IgE or the IC. A CD23-specific Ab or soluble CD23 significantly reduced the efficiency of IgE or IC transcytosis, suggesting a specific receptor-mediated transport by CD23. Transcytosis of both IgE and the IC was further verified in primary human airway epithelial cell monolayers. Furthermore, the transcytosed Ag-IgE complexes were competent in inducing degranulation of the cultured human mast cells. Because airway epithelial cells are the first cell layer to come into contact with inhaled allergens, our study implies CD23-mediated IgE transcytosis in human airway epithelial cells may play a critical role in initiating and contributing to the perpetuation of airway allergic inflammation.

Metabolically labeled monoclonal antibodies were used to measure the number of determinants per cell for an Epstein-Barr virus (EBV) cell surface antigen (EBVCS) (C. Kintner and B. Sugden, Nature [London] 294:458-460, 1981) which is expressed on the surface of EBV-transformed cells. The antigenic determinants were present approximately 5 X 10(5) times per in vitro-transformed cell. Immunoprecipitation followed by electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate indicated that four independent monoclonal antibodies to EBVCS recognized a protein of 47,000 daltons. The identification of EBVCS isolated from EBV-transformed cells grown in tunicamycin demonstrated that the antigen when isolated from cells grown without this drug was glycosylated. Finally, preclearing experiments with monoclonal antibodies to EBVCS or to HLA (class I products of the human major histocompatibility locus) and to beta 2-microglobulin indicated that EBVCS is not a major histocompatibility type 1 antigen.

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