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 t he lipids originated from the blubber of either a highly polluted St. Lawre nce beluga or a relatively uncontaminated Arctic beluga. After a period of 2 months, different immune functions were evaluated, including lymphoblasti c transformation, natural killer cell activity, plaque-forming cells, phago cytosis, oxidative burst, and immunophenotyping. For all assays, rats fed a St. Lawrence beluga blubber diet or a mixture of Arctic and St. Lawrence b eluga blubber diet were not different from control rats fed a diet containi ng Arctic beluga blubber. These results are inconsistent with the well-know n immunosuppressive effects of organochlorines in numerous species and with the lesions suggestive of organochlorine-related immunosuppression that ar e observed in St. Lawrence belugas. The lack of observable immunotoxic effe cts in rats fed contaminated beluga blubber might be explained by antagonis tic effects in the organohalogen mixture, by a response specific to the rat , by a strain-related lack of sensitivity to organochlorines, or by insuffi cient dose due to the shortness of the exposure period or the route of expo sure. (C) 1999 Academic Press.