WP 3.1 - Microdialysis in skin during local challenge in patients with anaphylaxis to foods and drugs.


IgE- as well as non?IgE mediated reactions can elicit anaphylaxis. In classical type I allergy, sensitization can be verified both by measurement of specific IgE and skin tests, but in patients with allergy to penicillin or insulin most patients are either IgE positive or skin test positive, although identical allergens are used in both tests. Another example of non-IgE mediated, mast cell driven reactions is inducible urticaria e.g. cold urticaria.



There are 3 parts of an allergic reaction:



In PART A factors activating the local mast cell at point of entry will be studied. The hypothesis is, that IgE positive patients reacting to insulin or penicillin do not react in skin due to lack of competent specific IgE on the skin mast cell.



Skin microdialysis, a technique for measuring extracellular substances, will be performed to estimate levels of histamine and other mediators released from skin mast cells. In order to enrich the local environment i.e. increasing the availability of specific IgE or other activators binding to local mast cells in the skin, patients will be pretreated with autologous serum, containing specific IgE against the allergen (wasp, penicillin, insulin) where after mast cells will be activated by intracutaneous injection of allergens and in the case of drugs also by direct application via the microfiber in the skin.


Results will be compared to identical experiments in patients with negative specific IgE and positive skin tests and in patients with cold urticaria and concomitant type 1 allergy. Further the effect of pretreatment of the skin in the area used for microdialysis with different drugs inhibiting the neurogenic activation (e.g. Capsaicine) will be investigated.

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