Examination of patients suspected as having hypersensitivity to iodinated contrast media with leukocyte migration test.

In vivo tests may be used for the diagnosis of allergy to iodinated contrast media (ICM); however, the tests do not provide definitive diagnosis and are associated with risks for patients. Diagnoses based on in vitro tests are limited, and there are almost no relevant studies. Herein, the authors examined involvement of allergic reaction from a multilateral standpoint in 39 patients suspected of having ICM allergies using leukocyte migration test (LMT). The positive rate of LMT was 44%. A comparison with the positive rate of LMT in drugs other than ICM (74%) indicated 30% difference, which was significantly low value, suggesting that there is poor involvement of these drugs in the allergic reaction. In LMT positives, 76% of hypersensitivity reactions were skin rash mainly erythema, and 18% was anaphylactic reactions. Cases considered as non-immediate hypersensitivity accounted for about 4 times as many as immediate-type hypersensitivity. In examination of relevancy between a history of drugs or food allergies, the incidence of ICM allergies was 35%. There is a high possibility that these adverse reactions were caused by pseudoallergy to drug. It was suggested that most hypersensitivity reactions were skin rash related to non-immediate hypersensitivity, and approximately 20% of the reaction was immediate anaphylactic reaction. Therefore attention should be paid not only to immediate-type hypersensitivity but also delayed reactions. Moreover, it was considered that patients with past history of drug or food allergies have a high potential for manifestation of the reactions.