Detection of Fc epsilon RI alpha in Human PBMCs by Flow Cytometry.
Human peripheral blood mononuclear cells (PBMCs) were stained with Mouse Anti-Human ENPP‑3/CD203c Fluorescein‑conjugated Monoclonal Antibody (Catalog # FAB5756F) and either (A) Mouse Anti-Human Fc epsilon RI alpha PerCP‑conjugated Monoclonal Antibody (Catalog # FAB6678C) or (B) Mouse IgG2B PerCP Isotype Control (Catalog # IC0041C). View our protocol for Staining Membrane-associated Proteins.
Preparation and Storage
The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage
Protect from light. Do not freeze.
12 months from date of receipt, 2 to 8 °C as supplied.
Background: Fc epsilon RI alpha
The alpha subunit of the high affinity IgE receptor (Fc epsilon RI alpha or Fc epsilon RIA) is a 45-48 kDa IgE‑binding type I transmembrane glycoprotein of the multichain immune recognition (MIRR) family (1, 2). The receptor, Fc epsilon RI, is a tetrameric complex of one alpha, one beta and two disulfide-linked gamma subunits ( alpha beta gamma 2) on mast cells and basophils (1). An alternate trimeric form ( alpha gamma 2) is expressed on human, but not rodent, mast cells, basophils, eosinophils, visceral smooth muscle, platelets, intestinal columnar epithelium and professional antigen presenting cells (3). While the gamma subunit is essential for expression of Fc epsilon RI alpha on the cell surface and for cell signaling, the beta subunit, when present, increases the halflife of the Fc epsilon RI complex on the cell surface (3, 4). An isoform of the beta subunit, beta T, blocks processing of the alpha subunit and its cell surface expression (2, 3, 5). Human Fc epsilon RI alpha cDNA encodes 257 amino acids (aa) including a 25 aa signal sequence, a 180 aa extracellular domain that contains two Ig‑like domains that bind IgE plus an endoplasmic reticulum retention motif, a 21 aa transmembrane sequence and a 32 aa cytoplasmic domain (1, 3, 6). Over aa 26-205, human Fc epsilon RI alpha shares 52% aa sequence identity with mouse Fc epsilon RI alpha. Binding of IgE alone increases surface expression of Fc epsilon RI, while crosslinking of IgE/Fc epsilon RI complexes by IgE ligands (allergens) initiates receptor internalization and signaling (2, 4, 5). Mast cell and basophil activation by IgE/Fc epsilon RI crosslinking causes degranulation, resulting in the release of histamine, leukotrienes, prostaglandins, and other mediators of immediate‑type and late‑phase allergic reactions. Circulating autoantibodies that crosslink Fc epsilon RI alpha are often found in patients with chronic urticaria (7). Fc epsilon RI on human antigen presenting cells mediates uptake and processing of allergens for presentation by class II MHC (2, 3). Fc epsilon RI expression on human DC and Langerhans cells is up‑regulated during allergic reactions (atopy) and correlates with serum IgE concentration (3).
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