ANTIBIOTICS AND CYTOKINE PRODUCTION BY HU MAN MONOCYTES

Antibiotics do not act alone but in conjunction with the host defence system. In particular, it has been shown that antibiotics can modify c ytokine production. The authors reported here the effects of antibioti cs which penetrate inside the cells, such as quinolones and macrolides , on the capacity of blood monocytes to produce IL-Ialpha, IL-1beta, T NFalpha and IL-6 in response to endotoxin. Antibiotics can exert a dif ferential effect on cytokine production : in fact, quinolones, in vitr o, at concentrations higher than 25 mug/ml decreased IL-1beta, TNFalph a and IL-6, while they do not modify IL-1alpha. Moreover, ciprofloxaci n orally administered (25 mg/kg for 7 days) transitory increased cytok ine production. These results are discussed in terms of tissue concent ration. Among the same family of antibiotics such as macrolides, diffe rences on cytokine modulation were observed : spiramycin and erythromy cin increased IL-6 production while roxithromycin did not exert any si gnificant effect. All these results tend to prove that some antibiotic s are immunomodulators ; however interactions between antibiotics and immune responses are complex and studies with patients with infections will be necessary to a better understanding of these relationships.