RAST

Clinical significance
Class E immunoglobulins are involved in the early stages of allergic reactions; produced mainly in the mucous membranes of the airways and gut, IgE bind by one end (Fab) to the antigens they are specifically directed against and by the other end (Fc) to basophils or their tissue counterparts, mast cells, which in turn release the substances (including histamine) responsible for the symptoms.
The presence of IgE specifically directed against a particular antigen makes it possible to identify the trigger of the allergic reaction and therefore prevent it, by avoiding exposure or by selectively immunising the person.
Testing for individual specific IgE should be preceded by a careful history to identify the route of contact (inhaled, food, skin contact) and the allergen family involved (e.g. grasses, trees, moulds, etc.).
Tests that use recombinant proteins to detect the corresponding IgE are more specific than classic RAST and can also explain cross-reactions between substances that contain the same protein, such as birch, apple, celery and carrot (see also specific IgE, ISAC test)