ELEVATED LEVELS OF THE EOSINOPHIL GRANULE MAJOR BASIC-PROTEIN IN THE SPUTUM OF PATIENTS WITH BRONCHIAL-ASTHMA

Abstract

The eosinophil granule major basic protein (MBP) is toxic to parasites and mammalian cells. Because eosinophilia is characteristic of asthma, the effect of MBP on bronchi was tested and sputa assayed for this protein. MBP damaged bronchial epithelium in vitro and produced changes that mimicked those in asthma. Radioimmunoassay of sputa from 100 consecutive patients with respiratory diseases revealed MBP levels above 0.1 .mu.g/ml in 13 patients, and 11 of these had asthma. In 15 patients hospitalized for asthma, MBP levels of sputum were markedly elevated. Treatment with bronchodilators and glucocorticoids caused an increase in peak expiratory flow rate, a reduction in blood eosinophils and a decrease in the serum and sputum levels of MBP. Eosinophil granule constituents are apparently released into the bronchi in asthma. Measurement of sputum MBP may be useful in identify ing asthma. The possibility that the eosinophil damages bronchial epithelium in asthma is discussed.