Familial exercise-induced anaphylaxis.

An 18-year-old hispanic male, his two brothers, father, two paternal uncles, and paternal grandfather experienced cutaneous and cardiorespiratory symptoms during vigorous exercise beginning at about 10 years of age. The propositus was challenged by running to exhaustion and by immersion in hot water. In neither case were allergic signs or symptoms noted; however, plasma histamine rose from undetectable levels to 1.0 and 3.7 ng/ml, respectively. Furthermore, C2 and C5 were significantly reduced and fell during exercise.