Boost of mucosal secretory immunoglobulin A response by clarithromycin in paediatric influenza

Background and objective: The antiviral neuraminidase inhibitor oseltamivir (OSV) is used to treat influenza. The macrolide clarithromycin (CAM) is used to treat bacterial infections and has anti-inflammatory and immunomodulatory activities. This retrospective study investigated the immunomodulatory effects of CAM in children presenting with influenza A. Methods: The study recruited 40 children with acute influenza, and grouped them according to the treatment received: 5-day treatment with OSV (n = 14), CAM (n = 8), OSV + CAM (n = 12) and untreated (n = 6). The before and after treatment comparisons were made of the level of secretory IgA (sIgA) against influenza A virus (H3N2) and (H1N1), total sIgA, viral RNA copy numbers in nasopharyngeal aspirates and disease symptoms. Results: Infection induced anti-viral mucosal sIgA in the nasopharyngeal aspirates of most patients of all treatment groups. Particularly prominent increases in the levels were found in the CAM and OSV + CAM groups. Low induction of anti-viral sIgA was observed in the OSV group, but the addition of CAM to OSV augmented sIgA production and restored local mucosal sIgA levels. The frequency of residual cough in the OSV + CAM group was significantly lower than in the other groups including the group treated with OSV. Conclusions: CAM boosted the nasopharyngeal mucosal immune response in children presenting with influenza A, even in those treated with OSV who had low production of mucosal anti-viral sIgA, and alleviated the symptoms of influenza.