EFFECTS OF GREAT-LAKES FISH CONSUMPTION ON THE IMMUNE-SYSTEM OF SPRAGUE-DAWLEY RATS INVESTIGATED DURING A 2-GENERATION REPRODUCTIVE STUDY -II - QUANTITATIVE AND FUNCTIONAL-ASPECTS

The effects of Great Lakes fish contaminants on several quantitative a nd functional aspects of the immune system were investigated in the fi rst (F-1) and second (F-2) generations of Sprague-Dawley rats. The F-0 rats were fed either a control diet or diets containing 5 or 20% lyop hilized chinook salmon hom the Credit River of Lake Ontario (LO) and O wen Sound point of Lake Huron (LH). The F-1 and F-2 pups were exposed to fish in utero, through the dam's milk to 21 days old, and through t he dam's respective diets to 13 weeks of age. The study included an F- 1-reversibility (F-1-R) phase in which rats at 13 weeks of exposure to fish or control diets were switched to the control diet for 3 months. The most outstanding finding was a statistically significant increase in absolute spleen leukocytes and absolute and percentage lymphocytes in the F-2 male rats fed the LH fish diets compared to the control an d to those fed the LO fish diets with the 20% fish diets having higher cell numbers compared to the LO-5% fish diets. A parallel increase in the T-helper/inducer T-lymphocyte subset numbers was observed. Increa sed but statistically insignificant plaque-forming cell (PFC) numbers were obtained in the F-2 male rats fed the LH fish diets compared to t hose fed the LO fish diets and in the F-1-R female group of rats fed t he LH fish diet compared to those fed the LO fish diets. Phagocytosis by resident peritoneal macrophages was significantly increased in the F-1 male and F-2 female rats fed the fish diets compared to the contro l. The phagocytic activity was significantly higher in the F-2-generat ion male and female rats fed the LO diets compared to those fed the LH diets. Other parameters including lymphocyte transformation in respon se to mitogens, the number of Listeria monocytogenes bacteria survivin g in the rat spleens, and the natural killer cell activity were not af fected significantly by any of the treatments. Overall, the effects of diets containing chinook salmon from the LO and LH sources on the inm une system of rats were minimal and were on quantitative rather than o n functional aspects of the system. Further focused research would be required in order to establish conclusively that the immune system of cohorts who ingest Great Lakes fish frequently is at a greater risk fo r adverse effects. (C) 1998 Academic Press.