Based on the affect of azithromycin on inflammatory cell influx, we proposed that azithromycin-dependent attenuation of allergic airway inflammation would also be associated with decreased concentration of BAL fluid cytokines and chemokines. Compared to ovalbumin sensitized and challenged mice treated with PBS solution, treatment with azithromycin attenuated the expression of multiple BAL fluid cytokines, chemokines, and growth factors as measured by multiplex flow cytometry based assay (Fig 3A–F, column 4 vs 5). Importantly, we observed a statistically significant azithromycin- dependent decrease in interleukin (IL)-13 and IL-5, and a trend toward a decrease in IL-4, proteins known to mediate allergic airway inflammatory phenotypes in the airway (eg, mucous cell metaplasia and eosinophilic inflammation). In addition, azithromycin attenuated the expression of multiple other chemokines and inflammatory mediators (CCL2/JE, CCL3/macrophage inhibitory protein [MIP]-1α, CCL4/MIP-1β, CXCL1/KC, IL-1α, IL-10, and granulocyte-macrophage colony-stimulating factor), but had no effect on concentration of IL-6, IL-9, IL-1β, IL-12 p40, IL-17, granulocyte colony-stimulating factor, or CCL5/regulated on activation, normal T-cell expressed and secreted (RANTES) [data not shown]. The levels of IL-2, IL-3, IL-12 p70, interferon-γ, tumor necrosis factor-α, and eotaxin were below levels of detection. Since high concentrations of mouse BAL fluid eotaxin were previously identified in the ovalbumin model of allergic asthma,27 we measured BAL fluid eotaxin concentrations by using a more sensitive ELISA assay. Compared with naive mice, mice that underwent the ovalbumin challenge and sensitization followed by PBS solution treatment resulted in higher eotaxin BAL fluid concentrations (0.5 ± 0.1 pg/mL vs 23.1 ± 5.6 pg/mL, respectively; p < 0.01), but azithromycin treatment in mice had no significant effect on eotaxin BAL fluid concentration (20.4 ± 9.9 pg/mL; p = 0.35). Collectively, these data demonstrate that azithromycin attenuated ovalbumin-dependent expression of BAL fluid inflammatory mediators, several of which are critical for development of an allergic inflammatory response.