Abstract
Ciprofloxacin, pefloxacin, norfloxacin, and ofloxacin were investigated for immunomodulatory activity on humoral and cell-mediated immune responses. Ciprofloxacin and pefloxacin altered the humoral immune responses of mice to sheep red blood cells. This effect was not exhibited by norfloxacin or ofloxacin. All four quinolones did not alter cell-mediated responses. When these antimicrobial agents were tested for their interaction with human polymorphonuclear phagocytic activity, all agents suppressed this activity. In addition, all except norfloxacin showed anti-inflammatory activity.