Incidence and significance of precipitating antibodies in occupational and non-occupational extrinsic non-atopic (type III) asthma (bronchial asthma with precipitins).

Precipitating antibodies against different organic enviromental dusts were studied in 37 patients with suggestive symptoms of nonatopic bronchial asthma, comparatively with a group of 4 patients with atopic asthma and with a group of asymptomatic subjects, exposed to the same organic dusts as the majority of patients. Precipitins were found present in over 75% of the sera from patients with infectious type non-atopic asthma and were associated with positive semidelayed type skin tests as well as with positive bronchial provocation tests a few hours after antigen inhalation. No precipitins were found in the sera from patients with atopic asthma. Precipitating antibodies were also found but in lower percentages (30%) and at lower titers, in clinically asymptomatic subjects who were occupationally exposed to the respective antigens. It was demonstrated that the presence of precipitins in the sera of patients with bronchial asthma is a valuable diagnostic element which confirms the clinical and anamnestic data. The pathogenic role of precipitins is not yet clear. It might be related to the amount of these precipitins in the serum.