Immunoglobulin E.

The part of the allergy reaction that is IgE-dependent. The uppermost body with antigen contact is not the B cell, but the APC, which in turn initiates the differentiation of the B cell to the plasma cell through interleukins.

Immunoglobulin E ( IgE ) is an antibody that is primarily intended to ward off endoparasites . He is also responsible for allergies .

Of all antibody isotypes, IgE was the last to be discovered, namely only in 1966 by the Kimishige and Teruko Ishizaka couple . This late first description can be explained by the comparatively very low concentrations of free IgE antibodies in the serum . While IgG ₁ antibodies typically occur in concentrations around 9 mg / ml serum, the IgE concentrations are around 300 ng / ml serum. IgE antibodies are the only antibodies that are predominantly cell-bound.

IgE has the ability to bind to mast cells or basophilic granulocytes via Fc receptors and stay there for years in the body. If it binds an allergen , it causes the mast cell to release substances that trigger an allergy - mainly histamine . It also plays an important role in warding off parasites and worms . An IgE-dependent cytotoxicity mediated by eosinophilic granulocytes is assumed . It makes up less than 1% of all immunoglobulins in the body and has the typical Y shape, similar to IgG or IgD , but a longer stem.

Significance in medical diagnostics

The concentration of total IgE plays a significant role in the assessment of allergic diseases, in particular eosinophilic lung infiltrates , eosinophilic gastroenteritis and allergic alveolitis (e.g. in the farmer's lung ), vasculitides such as granulomatosis with polyangiitis , the churg Strauss syndrome and allergic bronchopulmonary aspergillosis . IgE is also often increased in parasitoses . The IgE determination is useful for immune defects such as T-cell defects or hyper-IgE syndrome , but also for forms of urticaria , Quincke's edema or unclear exanthema .

literature

• Charles Janeway , Paul Travers, Mark Walport, Mark Shlomchik: Immunology. 5th edition, Spektrum Akademischer Verlag, Heidelberg 2002, ISBN 3-8274-1079-7 ; Online version in English , 5th edition, 2001.

Individual evidence

1. ↑ H. Renz et al .: DGAKI guideline for in-vitro allergy diagnostics of the Immunology Section of the DGAKI (development stage S1, ver. April 29, 2009).

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