The effects of ochratoxin A on the immune response of Swiss mice.

The acute intraperitoneal toxicity of ochratoxin A (OA) for adult female Swiss mice is presented. The seven-day LD(50) was calculated to be 48 +/- 3.2 mg/kg. Daily intraperitoneal administrations of 10 mg OA/kg resulted in 50% mortality by the tenth day of injection. Clinical symptoms included depression, huddling, roughened hair coats, humped backs and reduced weight gains. Mice injected intraperitoneally daily for 50 days with 5 mg OA/kg had a significantly (P<0.01) depressed antibody response to killed Brucella abortus. In contrast, oral administrations of OA at 4 ppm in feed for 50 days did not depress titre levels. Ochratoxin A also significantly (P<0.01 intraperitoneal; P<0.05 oral administrations) reduced body weight gain over the period of the trials. Neither oral nor intraperitoneal administration of OA for 50 days affected the response of mice to sheep red blood cells although both the number of antibody-forming cells and the number of cells per spleen were significantly lowered (P<0.01) by cyclophosphamide. Both spleen and body weights were significantly lowered (P<0.05) in the groups given OA. There was a significant depression of blast transformation (P<0.01) in mice treated intraperitoneally with either OA or cyclophosphamide and stimulated with concanavalin A; oral administration of OA did not depress blast transformation. It would appear that lower levels of exposure, e.g. 4 ppm OA in feed, do not cause depression of the immune response of mice. The depressive effect seen at much higher levels may be a result of a nonselective toxic effect.