Date of Award
Doctor of Philosophy
Theses & dissertations (Interdisciplinary)
Alveolar macrophages were harvested from rabbits that had been given oral dosages of 0, 0.25, or 0.5 mg T-2 mycotoxin/kg/d for 21 days. A dosage of 0.75 mg/kg/d was given to a group of 5 rabbits, but 4 died during the 21-day period. The harvested macrophages were used in an in vitro phagocytosis assay using killed Aspergillus fumigatus Fres. conidia as ingestion particles. Phagocytosis was significantly reduced (p < 0.01) in cultures using serum from 0.5 mg/kg/d T-2 treated rabbits and macrophages from either untreated or T-2 treated rabbits. Weight gains, serum alkaline phosphatase, serum sorbitol dehydrogenase, and serum bacteriostasis were significantly reduced (p < 0.05) in rabbits given 0.5 mg/kg/d T-2 toxin. These changes also were found in the 0.75 mg/kg/d group in addition to a significant reduction (p < 0.05) in packed cell volume and total and differential leukocyte counts except for neutrophil counts which declined, but not significantly. The major histopathologic changes that occurred in most T-2 treated rabbits were centrolobular hepatocellular swelling, mild portal and periportal fibrosis, and lymphocyte necrosis within secondary lymphoid tissues, with lesions of greater severity occurring in the 0.75 mg/kg/d group. The effects of T-2 toxin on the phagocytic and cell-mediated immune response to aspergillosis were investigated in rabbits given oral dosages of 0.5 mg T-2 toxin/kg/d for 17 or 28 days and exposed to aerosols of A. fumigatus conidia from Days 7-16. Controls consisted of groups of rabbits given this dosage of T-2 toxin only or exposed to aerosols of A. fumigatus conidia only. Aspergillosis caused leukocytosis and an increased antibody response to A. fumigatus as measured by indirect hemagglutination (IHA). Defense mechanisms to A. fumigatus infection were compromised by T-2 treatment evidenced by the severity and extent of lung lesions, greater numbers of hyphal elements observed in lesions, and a greater number of A. fumigatus colony-forming units isolated. Also, T-2 toxin ingestion caused a decreased antibody response (IHA) to A. fumigatus in the aerosol-exposed rabbits. Histopathologic changes due to T-2 toxin ingestion were similar to those described above. Hematologic changes in T-2 treated rabbits included leukopenia, anemia, and increased numbers and morphologic changes in nucleated erythrocytes by Day 21, followed by a regenerative response.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Kayleen Ann Niyo
Niyo, Kayleen Ann, "Effects of T-2 mycotoxin ingestion on selected resistance mechanisms and on experimentally induced aspergillosis in rabbits " (1987). Retrospective Theses and Dissertations. 11714.