Activated eosinophils in nasal polyps: a comparison of asthmatic and non-asthmatic patients

Objectives: There is a recognized clinical association between nasal polyps and asthma. Nasal polyps and the airways of asthmatic patients demonstrate marked eosinophilia suggesting that this inflammatory cell may have a key role to play in both conditions. The objective of this study was to determine whether nasal polyps from patients with asthma had a greater density of activated eosinophils than patients with no associated respiratory disease. Design: Archived specimens were retrieved from patients who had undergone nasal polyp surgery and their case notes reviewed. Activated eosinophils were identified using immunohistochemistry for a monoclonal antibody to secreted eosinophil cationic protein (EG2). Setting: Teaching hospital otolaryngology unit. Participants: Consecutive patients who had undergone nasal polyp surgery in 1994 were recruited. The diagnosis of asthma was based on a documented physician diagnosis and appropriate drug treatment. Twenty-four asthmatic and 35 non-asthmatic patients were studied. Main outcome measures: Eosinophil density was measured using a standardized counting technique. Results: Asthmatic patients were significantly more likely to have had previous polyp surgery (chi-square test: P < 0.05). Areas of intense eosinophilia were identified in all samples. There was a significant greater degree of activated eosinophilia in the asthmatic patients (t-test: P < 0.05). Conclusions: We have demonstrated a higher number of previous operations in asthmatic patients, and also a greater degree of activated eosinophilia in asthmatic polyps compared with non-asthmatics. This would suggest that eosinophil activity has a role to play in the pathogenesis of nasal polyps.