Immunotoxicity assessment of gentamycin and liquamycin

Rats were injected with gentamycin (GEN) or the oxytetracycline, liquamycin 200 (LA200), and multiple immune responses were measured to assess the immunotoxicity of these antibiotics. Animals were treated by sc or im injection for 12 days with either GEN or LA200 given at a therapeutic dose or at 10-, 50-, or 100-fold greater concentrations. The following immune parameters were assessed in each animal: delayed-type hypersensitivity (DTH), natural killer (NK) cell cytotoxicity, antibody production, and synthesis of interleukin 2 (IL2) and gamma interferon (IFN). The DTH response and IFN production in GEN- and LA200-injected animals were suppressed in a dose-dependent manner. Production of IFN was significantly suppressed in all groups treated with LA200. Suppression of DTH was evident when GEN or LA200 were given at the recommended therapeutic dose. Both LA200- and GEN-treated rats had suppressed NK cell cytotoxicity, but only at the highest dosages. Antibody production was suppressed in a dose-dependent manner in LA200-treated rats. Synthesis of IL2 was suppressed in rats treated with the high dose of GEN. Body weight loss occurred, and hepatic and renal toxicity were apparent at the 2 highest dosages of GEN or LA200. It was apparent that relatively high doses of GEN and LA200 can suppress specific and non-specific cell-mediated immune responses. Also, the data suggest the certain immune responses (eg, DTH reaction and possibly IFN production) may be suppressed at the recommended therapeutic doses in the absence of other signs of toxicity. These results indicate that these antibiotics should not be administered at doses or exposure periods in excess of those recommended.(ABSTRACT TRUNCATED AT 250 WORDS)