Effects of T-2 mycotoxin ingestion on phagocytosis of Aspergillus fumigatus condidia by rabbit alveolar macrophages and on hematologic, serum biochemical, and pathologic changes in rabbits

Rabbits were given T-2 mycotoxin orally at 0, 0.25, 0.5, and 0.75 mg/kg of body weight/day for 21 days. Only rabbits in the 0.75 mg/kg/day group (4 of 5 rabbits) died. Alveolar macrophages were harvested on day 22 and used for in vitro phagocytosis of killed Aspergillus fumigatus conidia. Cultures included sera from untreated rabbits or rabbits treated with T-2. Phagocytosis was significantly (P < 0.01) reduced in cultures that used serum from rabbits treated with 0.5 mg of T-2kg/day and alveolar macrophages from untreated rabbits or rabbits treated with T-2. There was little reduction in phagocytosis when alveolar macrophages from rabbits treated with T-2 and normal serum were used. Ingestion of 0.5 mg of T-2 toxin/kg/day significantly (P < 0.05) reduced weight gain, serum alkaline phosphatase activity, serum sorbitol dehydrogenase activity, and serum bacteriostasis. Similar changes were found in the 0.75 mg/kg/day group, as well as a significant (P < 0.05) reduction in PCV, total WBC, and differential leukocyte counts. Neutrophil counts decreased, but not significantly (0.05 < P < 0.10). Significant changes were not detected in alanine transaminase activity, aspartate transaminase activity, blood urea nitrogen concentration, or complement hemolytic activity. Histopathologic changes consisting of centrilobular hepatocellular swelling, mild portal and periportal fibrosis and lymphocyte necrosis within secondary lymphoid tissues developed in most rabbits treated with T-2. Thymic atrophy, bile duct reduplication, and lymphocyte depletion of secondary lymphoid tissues developed in the group given 0.75 mg/kg/day. Severity of lymphoid depletion in secondary lymphoid tissues was greatest in the appendix and decreased in the following order: appendix > sacculus rotundus > ileal Peyer patches > lymph nodes and spleen. In this study, we provide additional data showing that, at these oral doses of T-2 toxin, rabbits could be immunosuppressed, as evidenced by reduced alveolar macrophage phagocytosis and histopathologic changes in lymphoid tissues. Also, these doses caused reductions in weight gain, certain hematologic factors, and serum alkaline phosphatase and sorbitol dehydrogenase activities.