Oral aspirin challenges in asthmatic patients: a study of plasma histamine

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Abstract
Under carefully controlled conditions, 7 aspirin[ASA]-intolerant asthmatic patients were challenged with oral ASA and experienced respiratory tract reactions with a decline in forced expiratory volume in 1 s (FEV1), ranging from 26-64%. Venous blood samples collected during the challenges showed a rise in plasma histamine in all 7 patients. The increase in plasma histamine occurred at the onset of their respiratory reactions, and those patients with the most severe asthmatic responses had the highest and most prolonged levels of plasma histamine. The same ASA-intolerant asthmatic patients were able to ingest Maalox or sodium salicylate without untoward effects, decline in FEV1 values or changes in plasma histamine levels. Ten non-asthmatic individuals and 8 out of 10 asthmatic control patients were able to ingest ASA without any reactions or changes in their plasma histamine levels. Two asthmatic control individuals, with severe asthma requiring treatment with moderate dosages of corticosteroids, had elevated pre-challenge plasma histamine levels which increased during their ASA challenges despite the absence of respiratory reactions or changes in FEV1 values. It is possible that these 2 individuals were unsuspected ASA intolerant asthmatics. Asthmatic reactions to acetylsalicylates are associated with release of histamine into plasma in the subgroup of asthmatic patients with the aspirin-intolerance syndrome. Such a finding suggests that histamine may be one of the mediators of bronchospasm in aspirin-induced asthma.