Abnormal responses of the autonomic nervous system in food-dependent exercise-induced anaphylaxis.

We investigated abnormal responses of the autonomic nervous system and measured plasma histamine levels before and after exercise challenge following food ingestion in four patients with food-dependent exercise-induced anaphylaxis. The patients' histories and the radioallergosorbent tests showed that food-dependent exercise-induced anaphylaxis resulted from preexercise-ingestion of shrimp, hen's egg, and any food in two patients, one patient and one patient, respectively. The plasma histamine level increased in only one of four patients when the exercise challenge followed the ingestion of nonoffending foods. Our investigation of changes in the autonomic nervous system before and after food-exercise challenge in all patients included comparing results obtained after the food-exercise challenge in controls and comparing results obtained before food-exercise challenge in the patients. After food-exercise challenge, systolic blood pressure significantly decreased and the heart rate increased during the postural test, heart rate tended to decrease in the Aschner test, and the increase of systolic blood pressure was reduced in the cold pressor test. After food-exercise challenge, the parasympathetic nervous activity increased and responsiveness of the sympathetic nervous system was reduced. Food-dependent exercise-induced anaphylaxis may therefore occur in relation to allergic reactions and abnormality of the autonomic nervous system.