Membrane-bound immunoglobulin E receptor (mIgE)

Membrane-bound immunoglobulin E (mIgE) is the isoform of IgE expressed on the surface of B cells as part of the B cell antigen receptor (BCR) complex after class switch recombination to the epsilon (ε) heavy chain. This membrane form serves as the antigen-specific receptor that allows B cells to recognize allergens and respond by activating and ultimately differentiating into IgE-secreting plasma cells. In humans, mIgE can exist in multiple isoforms generated by alternative splicing, including a variant with an extracellular membrane-proximal domain that restricts surface expression and B cell activation[1][2]. mIgE+ B cells are rare in vivo and have a short lifespan, functioning mainly as transient precursors to plasma cells[2]. Interactions between mIgE and accessory molecules such as CD23 on B cells are crucial for regulating IgE synthesis and homeostasis, with implications in the pathogenesis and therapy of allergic diseases[5][6].\n\nKey points:\n- mIgE is not to be confused with secreted IgE (the antibody in plasma); mIgE acts as a B cell receptor before secretion[3][4].\n- Targeting mIgE directly is a potential but challenging strategy in allergy therapy due to safety concerns regarding unwanted immune activation[1].\n- Omalizumab and related anti-IgE antibodies primarily target circulating IgE, indirectly reducing mIgE+ B cells but do not bind membrane-bound IgE to avoid triggering degranulation[1].

Other names

Membrane IgEmIgE receptorB cell antigen receptor IgE isotypesurface IgEIgE-BCR

Inhibition of IgE binding to high-affinity FcεRI receptors on mast cells (by lowering available IgE); Reduction of IgE-expressing B cell survival by depleting free IgE (indirect effect).