Effect of long-term, low-dose clarithromycin on T helper 2 cytokines, eosinophilic cationic protein and the 'regulated on activation, normal T cell expressed and secreted' chemokine in the nasal secretions of patients with nasal polyposis

Background: Little is known about the effects of macrolides on the cytokines and chemokines that modulate the function of eosinophils in nasal polyposis. Methods: Twenty-two non-allergic and 18 allergic patients with nasal polyps were administered clarithromycin 500 mg/day (single oral dose) for eight weeks. We measured the nasal secretion levels of the T helper 2 (also known as Th2) cytokines interleukin 4, 5 and 6, the 'regulated on activation, normal T cell expressed and secreted' (also known as RANTES) chemokine, and the eosinophilic cationic protein, before and after treatment. Results: After clarithromycin treatment, we found reduced levels of the 'regulated on activation, normal T cell expressed and secreted' chemokine in samples from both non-allergic and allergic patients (p < 0.05). Clarithromycin treatment decreased the levels of eosinophilic cationic protein only in non-allergic patients (p < 0.05), and decreased the level of interleukin 6 only in allergic patients (p < 0.05). Decreased levels of the 'regulated on activation, normal T cell expressed and secreted' chemokine were associated with a reduction in polyp size both in non-allergic and allergic patients. Conclusion: Clarithromycin has a strong anti-inflammatory effect in nasal polyposis, but has different immunomodulatory effects in allergic and non-allergic nasal polyposis patients.