HEMATOPOIETIC ALTERATIONS AFTER EXPOSURE TO T-2 MYCOTOXIN

Adult mice were exposed by oral gavage to 0.75, 1.25, or 1.75 mg/kg body weight T-2 mycotoxin for 5 consecutive days. Thymic atrophy on the 2nd day following cessation of dosing was profound, and was characterized by significant decreases in the total number of cells within all phenotypes defined by CD4 and CD8 cell-surface antigen expression. Further, the distribution of thymocytes within these phenotypes was significantly altered. Increased percentages of CD4(-)8(-) (DN) and decreased percentages of CD4(+)8(+) (DP) cells in thymuses from treated animals suggested that T-2 toxin may inhibit thymocyte maturation. In addition to thymus, the bone marrow of treated animals showed a highly significant hypocellularity, indicating that this hematopoietic compartment may also be targeted by T-2 toxin. A trend toward reduced splenic cellularity was additionally observed in exposed animals, but failed to reach significance. A significant decrease in the total number of both B and T-lymphocytes present within the spleen was observed, however. These data, taken together, indicate that effects at multiple hematopoietic compartments involved in the production of T-lymphocytes may contribute to the peripheral T-cell lymphocytopenia and T-cell mediated immunosuppression produced by T-2 toxin.