Bronchial hyperreactivity in allergic subjects.

Bronchial hyperreactivity was studied in 79 patients who gave a history of allergic symptoms. Twenty-nine of them suffered from rhinitis, 28 from eczema, 21 from urticaria and one from gastrointestinal allergy. Forced expiration in the first second (FEV1) was measured in each. If FEV1 was greater than 1 l a histamine challenge was done. Histamine (0.6 mg/ml) was inhaled by tidal breathing for one minute. FEV1 was measured before the inhalation and two min after cessation of the inhalation. If FEV1 dropped greater than 20% the inhalation was assessed as positive and the provocation was stopped. If the challenge was not positive another inhalation with histamine (2.4 mg/ml, l min) was done. If FEV1 dropped greater than 20% when measured two min after the inhalation the provocation was called positive. Twenty-two patients with rhinitis had a negative bronchial challenge, six had a positive. One of them had asthma, three suffered also from cough and/or serous sputum production, and two had hay fever. Out of 28 with eczema, 20 had negative histamine challenge and five a positive. Four of these suffered from daily cough and/or serous sputum production, one had no airway symptoms. Fifteen out of 21 suffering from urticaria had a negative histamine challenge, three had a positive. Two of them suffered from asthma and one complained of daily cough and/or serous sputum production. It is concluded that allergic subjects without symptoms from the airways, have a bronchial reactivity to inhaled histamine similar to the general population.