Guidelines for the clinical evaluation of occupational asthma due to high molecular weight (HMW) allergens. Report of the Subcommittee on the Clinical Evaluation of Occupational Asthma due to HMW Allergens.

Sensitization to HMW allergens is a relatively common immunopathogenic factor in occupational asthma. The mechanism of sensitization is an IgE-mediated, type I reaction. High molecular weight allergen refers to proteins and polymers of organic compounds over 5 kd and usually in the 20 to 50 kd range. In most cases diagnosis requires: 1. A high index of suspicion of job-related asthma. 2. Exposure to HMW compounds and clinical findings associated with such an exposure. 3. Confirmation of sensitization by appropriate in vitro or in vivo tests. 4. Confirmation of a pathogenic role by physiologic measurements in either a natural setting or during laboratory-controlled challenges.