Tracing IgE-Producing Cells in Allergic Patients
Department of Otorhinolaryngology, Medical University of Vienna, Vienna A-1090, Austria
NRC Institute of Immunology FMBA of Russia, Moscow 115478, Russia
Department of Clinical Immunology and Allergy, Sechenov First Moscow State Medical University, Moscow 119435, Russia
Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna A-1090, Austria
Author to whom correspondence should be addressed.
Cells 2019, 8(9), 994; https://doi.org/10.3390/cells8090994
Received: 16 July 2019 / Revised: 13 August 2019 / Accepted: 21 August 2019 / Published: 28 August 2019
(This article belongs to the Special Issue The Molecular and Cellular Basis for Allergies & Asthma)
Immunoglobulin E (IgE) is the key immunoglobulin in the pathogenesis of IgE associated allergic diseases affecting 30% of the world population. Recent data suggest that allergen-specific IgE levels in serum of allergic patients are sustained by two different mechanisms: inducible IgE production through allergen exposure, and continuous IgE production occurring even in the absence of allergen stimulus that maintains IgE levels. This assumption is supported by two observations. First, allergen exposure induces transient increases of systemic IgE production. Second, reduction in IgE levels upon depletion of IgE from the blood of allergic patients using immunoapheresis is only temporary and IgE levels quickly return to pre-treatment levels even in the absence of allergen exposure. Though IgE production has been observed in the peripheral blood and locally in various human tissues (e.g., nose, lung, spleen, bone marrow), the origin and main sites of IgE production in humans remain unknown. Furthermore, IgE-producing cells in humans have yet to be fully characterized. Capturing IgE-producing cells is challenging not only because current staining technologies are inadequate, but also because the cells are rare, they are difficult to discriminate from cells bearing IgE bound to IgE-receptors, and plasma cells express little IgE on their surface. However, due to the central role in mediating both the early and late phases of allergy, free IgE, IgE-bearing effector cells and IgE-producing cells are important therapeutic targets. Here, we discuss current knowledge and unanswered questions regarding IgE production in allergic patients as well as possible therapeutic approaches targeting IgE.