The necessity for dual food intake to provoke food-dependent exercise-induced anaphylaxis (FEIAn):: A case report of FEIAn with simultaneous intake of wheat and umeboshi

Background: Food-dependent exercised-induced anaphylaxis (FEIAn) is classified among the physical allergies, Many different food allergens have been reported, but the pathophysiology of FEIAn remains unknown. Furthermore, provocation tests with a suspected food do not always succeed in patients with FEIAn, Objective: We sought to clarify and investigate causative foods and mechanisms of FEIAn in a 14-year-old boy, In addition, we tested in vivo and in vitro effects of cromolyn sodium in the same patient. Methods: We used open challenge tests for the provocation of FEIAn and measured changes in plasma histamine levels and FEV1, In addition, we investigated the mechanism of FEIAn in this case with in vitro histamine release testing. Results: The patient was diagnosed as having FEIAn by provocation testing with a simultaneous intake of wheat and ume-boshi, but not when each food was eaten singly, followed by exercise. In addition, his plasma histamine level increased transiently and forced expiratory volume I, expressed as a percentage change from baseline, decreased significantly, A synergistic effect on in vitro histamine release testing with 2 kinds of the causative foods was shown. Administration of cromolyn sodium proved to be effective on both the in vitro and in vivo tests, Conclusion: This is the first report of FEIAn provoked by the test with a simultaneous intake of 2 kinds of food. This case might in part explain negative challenge test results in patients with FEIAn.