Immune functions in the Fisher rat fed beluga whale (Delphinapterus leucas) blubber from the contaminated St. Lawrence estuary.
In order to assess the immunotoxic potential of food naturally contaminated with PCBs and other organohalogens, Fisher rats were fed a diet in which the lipids originated from the blubber of either a highly polluted St. Lawrence beluga or a relatively uncontaminated Arctic beluga. After a period of 2 months, different immune functions were evaluated, including lymphoblastic transformation, natural killer cell activity, plaque-forming cells, phagocytosis, oxidative burst, and immunophenotyping. For all assays, rats fed a St. Lawrence beluga blubber diet or a mixture of Arctic and St. Lawrence beluga blubber diet were not different from control rats fed a diet containing Arctic beluga blubber. These results are inconsistent with the well-known immunosuppressive effects of organochlorines in numerous species and with the lesions suggestive of organochlorine-related immunosuppression that are observed in St. Lawrence belugas. The lack of observable immunotoxic effects in rats fed contaminated beluga blubber might be explained by antagonistic effects in the organohalogen mixture, by a response specific to the rat, by a strain-related lack of sensitivity to organochlorines, or by insufficient dose due to the shortness of the exposure period or the route of exposure.