The cellular antigen stimulation test (CAST) in the diagnosis of aspirin-sensitive rhinosinusitis

In about 14% of adults with nasal polyps aspirin and other nonsteroidal antiinflammatory drugs induce intolerance reactions. Their clinical symptoms often resemble immediate type hypersensitivity and consist of rhinosinusitis, asthma, angioedema and even anaphylactic shock. Antigen specific immune mechanisms are not involved. The diagnosis of immediate hypersensitivity reactions to drugs is based on history, clinical manifestation, and if possible on skin tests. Determination of specific IgE is mostly not reliable in diagnosing intolerance reactions. Provocation tests have limitations and may be harmful. Therefore, a cellular stimulation lest (CAST) was applied to measure the production of leukotrienes, which are known to be potent mediators of anaphylaxis. In 22 patients, partly with known pseudoallergy to nonsteroidal antiinflammatory drugs and partly with polypous rhinosinusitis we tested the releasibility of the leukocytes upon antigen stimulation in order to prove the clinical relevance. Stimulation of leukocytes with acetyl salicylic acid in combination with complement 5a yielded better results than acetyl salicylic acid alone. In two thirds of the patient's sera a significant pathological reaction was measured when using additional NSAID. This In-vitro-test may benefit those patients who cannot tolerate provocation tests and, therefore, is a valuable additional diagnostic tool for the allergist.