Total eosinophil counts in the management of bronchial asthma

Total eosinophil counts were investigated in asthmatic patients to determine their usefulness in the diagnosis and management of steroid-dependent asthma. Counts averaged 122 plus or minus 74 (S.D.) per mm-3 (65 untreated normal subjects) and 43 plus or minus 22 per mm-3 (six prednisone-treated normal subjects). Fifty-two patients with active bronchial asthma showed significant eosinophilia (greater than 350/mm-3 off and greater than 85/mm-3 on steroids), suggesting that eosinophilia is an important diagnostic feature of bronchial asthma. In 14 patients (60 observations), the counts showed significant inverse correlation with specific airway conductance--r equals 0.74, p less than 0.001--and with a variety of other measurements of bronchial dynamics and lung volumes, suggesting that the total eosinophil count reflects asthmatic activity and is useful for regulating steroid dosage and for early detection of exacerbations.