Macrolides, with the exception of the 16-membered ring type, have both anti-inflammatory and antibacterial functions [20, 21] . One of the important mechanisms of antiinflammatory action is the suppression of NF-κB activation [22] [23] [24] . Our recent studies show that RSV upregulates proinflammatory cytokines, such as IL-6, and chemokines, such as IL-8 and RANTES, in the respiratory epithelial cell line A549. Furthermore, the induction of chemokines by RSV is significantly suppressed by an antibiotic, fosfomycin, via suppression of NF-κB activation [25] . In the present study, CAM was shown to suppress IL-6, IL-8, and RANTES, which are induced by RSV infection, at concentrations of 10 and 100 μg/mL. Patel et al. reported that the concentration of CAM in fluid of the bronchopulmonary epithelial lining was 34.2±5.16 μg/mL at 4 h, 23.01±11.9 μg/mL at 12 h in healthy adults orally administered CAM 500 mg [31] . We observed that CAM did not affect RSV replication even at a concentration of 100 μg/mL. However, it is reported that respiratory virus, such as RSV [32] , rhinovirus [33, 34] , and influenza virus [35] , replication is suppressed by 14-membered ring macrolides, including CAM. The reasons of contradictory results between the report of Asada et al. [32] and our present study have been unclear. These two studies used different types of epithelial cells and different experimental conditions of RSV infection. Asada et al. used primary human tracheal epithelial cells, and in contrast we used A549 cell line. Asada et al. carry out infection at a lower titer of RSV (10 −3 TCID 50 /cell) and measuring virus titer at a longer period (3-5 days) after infection. Our results indicated that suppression of the RSV-induced cytokines by CAM was not caused by the amount of replicated RSV. In other words, CAM was suggested to have suppressive activity of cytokine production independent of viral replication. Both IL-8 and RANTES, which are strongly upregulated during RSV infection, play important roles in pathogenesis [36, 37] . IL-8 primarily activates neutrophils and promotes their migration. RANTES is secreted from respiratory epithelial cells and promotes migration of eosinophils, basophils, monocytes, and neutrophils. In particular, RANTES is an efficient eosinophil chemoattractant involved in the pathogenesis of asthma [38] . CAM has been suggested to suppress the inflammatory disorders induced by RSV.