Eosinophilic inflammation of the airways is correlated with the severity of asthma. These cells are likely to play a part in the epithelial damage seen in this disease.

No abstract

The severity of asthma can be graded from mild intermittent to severe persistent. Airway inflammation is a feature of persistent asthma. We compared several markers of inflammation in mucosal biopsies and bronchoalveolar lavage fluid (BAL fluid) from 12 healthy control subjects, 24 patients with intermittent asthma, and 18 patients with mild-to-moderate persistent asthma. Epithelial shedding, eosinophil (EG2-positive cells), and activated T-cell (UCHL1) counts in biopsies, and ECP levels in BAL fluids were significantly increased in patients with intermittent asthma by comparison with control subjects and this increase was significantly greater for patients with persistent asthma. Alveolar macrophage activation (percentage of hypodense cells) and the thickness of the basement membrane were significantly increased in asthmatic subjects as compared with controls but there was no difference between the two asthmatic groups. Hyaluronic acid levels in BAL fluids were significantly increased in patients with persistent asthma by comparison with control subjects and patients with intermittent asthma. Mast cell numbers (toluidine blue) in biopsies and histamine or levels in BAL fluids were similar in the three groups. This study shows that airways inflammation is present in patients with intermittent asthma but to a lesser extent than in patients with persistent asthma.

Eosinophilic inflammation has been observed in the airways of patients with chronic obstructive pulmonary disease (COPD). A subset of patients clinically diagnosed as having COPD show a reversibility of airflow obstruction when treated with corticosteroids, and may consist of patients with features of asthma including reticular basement membrane thickening and eosinophilic inflammation. Twenty-five unselected patients clinically diagnosed as having COPD received a daily oral dose of 1.5 mg/kg body weight of prednisolone for 15 d to assess the relationships between the functional response to corticosteroids and the presence of features of asthma. Eosinophilic inflammation was characterized before the course of corticosteroid therapy by enumerating eosinophils in peripheral blood, bronchoalveolar lavage fluid (BALF), and bronchial biopsies, using EG2 monoclonal antibody, and by measurement of eosinophil cationic protein (ECP) in BALF. A response to treatment was defined by an increase in FEV1 of at least 12% from baseline values and an absolute value of 200 ml measured at the end of the treatment. Twelve of 25 patients responded to the treatment. By comparison with nonresponders, responders had a significantly larger number of eosinophils (p < 0.015), and higher levels of ECP (p = 0.013) in their BALF. The responders had a thicker reticular basement membrane than the nonresponders (p < 0.04). These results indicate that a response to prednisolone in patients diagnosed as having COPD might occur more readily in a subset of patients presenting with features of asthma.