EFFECT OF ANTIBIOTICS ON THE PHAGOCYTOTIC AND RESPIRATORY BURST ACTIVITY OF BOVINE GRANULOCYTES

The influence of antibiotics on respiratory burst (phorbol-12-myristat e-13-acetate (PMA)-stimulated luminol-enhanced chemiluminescence) and phagocytosis (flow cytometry) by bovine granulocytes was studied in vi tro. Phagocytosis was impaired by 1000 mu g/ml of oxytetracycline, chl oramphenicol, erythromycin and spiramycin. All antibiotics, except sul phadiazine, decreased chemiluminescence at 1000 mu g/ml or lower conce ntrations. Enrofloxacin increased chemiluminescence. The inhibition by oxytetracycline and danofloxacin was due to absorption of the light e mitted by luminol at 425 nm. Oxytetracycline, ceftiofur, spiramycin an d erythromycin affected the myeloperoxidase-H2O2-halide system. Ceftio fur, penicillin and danofloxacin showed scavenging effects on H2O2 and OCl-. Penicillin and ceftiofur might interfere with luminol. Chloramp henicol, penicillin and ceftiofur affected the production of superoxid e radicals. In summary, the observed effects of antibiotics might be o f importance during treatment of infectious diseases in normal and imm unocompromised animals. However, before classifying a drug as immunosu ppressive, attention has to be paid to possible interference with the chemiluminescence assay. (C) 1997 Elsevier Science B.V.