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 bo dy weight T-2 mycotoxin for 5 consecutive days. Thymic atrophy on the 2nd day following cessation of dosing was profound, and was characteri zed by significant decreases in the total number of cells within all p henotypes defined by CD4 and CD8 cell-surface antigen expression. Furt her, the distribution of thymocytes within these phenotypes was signif icantly altered. Increased percentages of CD4(-)8(-) (DN) and decrease d percentages of CD4(+)8(+) (DP) cells in thymuses from treated animal s suggested that T-2 toxin may inhibit thymocyte maturation. In additi on to thymus, the bone marrow of treated animals showed a highly signi ficant hypocellularity, indicating that this hematopoietic compartment may also be targeted by T-2 toxin. A trend toward reduced splenic cel lularity was additionally observed in exposed animals, but failed to r each significance. A significant decrease in the total number of both B and T-lymphocytes present within the spleen was observed, however. T hese data, taken together, indicate that effects at multiple hematopoi etic compartments involved in the production of T-lymphocytes may cont ribute to the peripheral T-cell lymphocytopenia and T-cell mediated im munosuppression produced by T-2 toxin.