Clinical significance of eosinophilic cationic protein levels in nasal secretions of patients with nasal polyposis

Nasal polyps are characterized by eosinophilic infiltration, and frequently coexist with asthma, aspirin intolerance and allergy. Eosinophilic cationic protein (ECP) is a specific eosinophil granule protein released upon activation of eosinophils. We investigated the ECP levels in nasal secretions of patients with nasal polyposis (NP) in order to correlate them with disease severity and associated diseases and to compare ECP levels between patients with and without recurrence of NP after surgical treatment. A total of 78 patients who had surgery for NP were followed up for a minimum of 18 months. The presence of asthma, allergies or aspirin intolerance was noted. Nasal secretions were obtained 1 day before the surgery and during the follow-up period after surgery. Immunoassays were used to quantify ECP in nasal secretions and serum and interleukin (IL)-5 in nasal secretions. ECP levels in nasal secretions were higher in patients with asthma or aspirin intolerance than in patients without asthma or aspirin intolerance, while no significant differences were found between allergic and non-allergic patients. ECP levels in nasal secretions correlated significantly with IL-5 levels in nasal secretions, the degree of tissue eosinophilia and computed tomographic (CT) scores. In total, 30 patients (38%) developed recurrent NP during the follow-up period. Preoperative ECP and IL-5 levels in nasal secretions were significantly higher in patients with recurrence compared to patients without recurrence. During the follow-up period, patients without recurrence demonstrated a significant reduction in the ECP levels in nasal secretions, whereas there was no significant reduction in the ECP levels of patients with recurrence. The results of this study provide evidence that ECP levels in nasal secretions of patients with NP correlate with the presence of asthma or aspirin intolerance and severity of NP determined by CT scores.