Some antimicrobial agents have been reported to have immunomodulatory effects and to show synergy in their anti-inflammatory effects. To study the immunomodulatory effect of gatifloxacin (GFLX), a fluoroquinolone, we investigated its influence on the production of cytokines in human tonsillar lymphocytes. Erythromycin (EM) was employed as a positive control, having previously been reported as having immunomodulatory effects. Palatine tonsils were obtained from 21 patients, including 9 patients in recurrent tonsillitis (5 males and 4 females, mean 26.7 y. o.), 5 patients with hypertrophic tonsils (3 males and 2 females, mean 6.5 y. o.), and 7 patients with focal tonsillar disorders (1 male and 6 females, mean 42.6 y. o.). Informed consent was obtained from all patients to use their tonsils for this study. The tonsillar lymphocytes were stimulated by Staphylococcal enterotoxin B (SEB, 100ng/ml) and were incubated with GFLX (2, 4, 10, or 20μg/ml) or EM (0.5, 1, 5μg/ml) for 24 hours. Cytokine production (IL-8 and TNF-α) in the supernatant was measured by solid-phase ELISA. IL-8 production of tonsillar lymphocytes was significantly suppressed by EM in three groups and by GFLX in recurrent tonsillitis groups. TNF-α production of tonsillar lymphocytes was enhanced in the tonsillar hypertrophy group and focal tonsillar disorders group by GFLX; however, no significant influence was shown in tonsillar lymphocytes by EM. In conclusion, GFLX has immunomodulatory effects on tonsillar lymphocytes through the suppression of IL-8 production; in particular, the recurrent tonsillitis group may have shown synergistic anti-inflammatory effect with its anti-bacterial properties.
