Inhalation tests of bronchial hypersensitivity in pollen asthma.

Possible allergic causes of asthma are frequently investigated by determining the sensitivity of the skin to various extracts of potentially allergenic substances, but the results of skin tests may correlate poorly with other clinical indications of specific allergies. Bronchial sensitivity cannot always be inferred from skin sensitivity. Determination of the response of the bronchi to allergens introduced directly into the respiratory tract seems to be a more direct method of testing for allergic causes of asthma, since it tests the hypersensitivity of the bronchial tree which is responsible for the symptoms in asthma and simulates the usual mode of entry of the allergen as it occurs in asthma. Inhalations of allergens were found by Colldahl (1952) to produce wheezing, evident to the subject or to observers, in some asthmatics, and by Herschfus, Rubitsky, Beakey, Bresnick, Levinson, and Segal (1951), Schiller and Lowell (1952) and Herxheimer (1952) to produce changes in the spirogram. The object of this investigation was to try out inhalation tests of bronchial hypersensitivity and to determine whether they give results which are reliable, consistent, and specific. For this purpose we selected patients in whom asthma was strictly seasonal and clinically appeared to be due only to grass pollen. We gave them inhalations of grass pollen extract and assessed the bronchial response by spirometry, and studied the effect upon this response of pollen hyposensitization treatment.