Clinical, immunologic and psysiologic studies were undertaken to establish the role of hog trypsin dust in four cases of occupational asthma and to define the mechanism of this respiratory disease. Objective evidence was obtained that these patients, but not their asymptomatic co-workers, were allergic to trypsin, and that this fact accounted for their respiratory symptoms. Direct skin testing, passive transfer of IgE antibodies, antigen-mediated histamine release from peripheral blood leukocytes and airway obstruction in response to inhalation challenge indicated IgE-mediated, Type I hypersensitivity. These effects were induced by inactivated trypsin and were therefore independent of tryptic enzymatic activity. The data suggested that periodic skin testing for immediate sensitivity to organic dust would be an inexpensive and convenient screening procedure for early detection and prevention of some types of occupational asthma.
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