Eight of fourteen hay fever subjects had their first episode of wheezing following an aerosol inhalation of pollen extract. Sputum examinations confirmed the presence of many eosinophils within minutes after specific allergen challenge. The appearance of eosinophils in the sputum, the fall in FEV1, with cough, tightness, and wheezing, after specific allergen, and the subsequent response to bronchodilators indicate that these were indeed allergic changes simulating asthma in hay fever subjects. Eight hay fever subjects showed a significant decrease in FEV1 after Mecholyl and six after histamine inhalations. All of the twenty-five asthma patients tested and none of the nonatopic controls showed a significant decrease in FEV1 following Mecholyl and histamine challenge in the doses employed. In terms of bronchial sensitivity to the number of inhalations of the preparations used, the asthma patients were approximately twenty-seven times as sensitive to Mecholyl as the hay fever group, but only three and four times as sensitive to histamine and pollen inhalation, respectively. Antihistamines do not block or prevent induced bronchial obstruction in hay fever subjects and therefore should not be relied upon to prevent asthma. Finally, the method presented may be useful to determine which persons who have hay fever are later going to have asthma.
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