title: Cultured human mast cells are heterogeneous for expression of the high-affinity IgE receptor FcεRI.
abstract: OBJECTIVE
  We determined the density of FcεRI on mast cells cultured from cord (CBMC) and peripheral blood (PBMC) and studied the kinetics of the response through FcεRI.
  
  
  METHODS
  Mast cells were cultured from CD133+ progenitors from peripheral or cord blood. FcεRI was stabilized by culture with 2 μg/ml IgE. Cells were activated by addition of anti-FcεRI antibody (1 ng/ml-10 μg/ml). Maximal activation, sensitivity, and cooperativity were determined.
  
  
  RESULTS
  All cultures were homogeneous for tryptase and metachromasy. All cells expressing FcεRI could be activated by cross-linking FcεRI to upregulate CD63. PBMC bind 203,000 molecules of IgE/cell. Stabilization of FcεRI with IgE doubled the number of CD63+ cells (p = 0.0001) and increased the sensitivity (from 0.083 to 0.013 μg/ml anti-FcεRI) and the slope factor (from 10.8 to 68) of PBMC but not of CBMC. Anti-IgE reversed these effects (p = 0.0002) but did not reduce activation levels below that of cell lines not stabilized with IgE.
  
  
  CONCLUSIONS
  Baseline expression of FcεRI is independent of anti-IgE. The fraction of PBMC that binds high levels of IgE can be activated through FcεRI.
authors: Department of Respiratory Diseases, Aarhus University and Hospital, Aarhus, Denmark. hans.jurgen.hoffmann@ki.au.dk
authors: Hans Jürgen
authors: HJ
authors: Hoffmann
authors: Pernille Munk
authors: PM
authors: Frandsen
authors: Lars Harder
authors: LH
authors: Christensen
authors: Peter Oluf
authors: PO
authors: Schiøtz
authors: Ronald
authors: R
authors: Dahl
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology; D006412:Hematopoietic Stem Cells; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology / Q000378:metabolism; D015847:Interleukin-4 / Q000276:immunology / Q000378:metabolism; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011755:Pyrophosphatases / Q000378:metabolism; D017455:Receptors, IgE / Q000276:immunology / Q000378:metabolism*; D060149:Tetraspanin 30 / Q000378:metabolism; D053802:Tryptases / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000888:Antibodies, Anti-Idiotypic; C554586:CD63 protein, human; C427944:ENPP3 protein, human; D017455:Receptors, IgE; D060149:Tetraspanin 30; C026408:anti-IgE antibodies; D015847:Interleukin-4; D007073:Immunoglobulin E; D010727:Phosphoric Diester Hydrolases; D053802:Tryptases; D011755:Pyrophosphatases