Development of apoptosis and changes in lymphocyte subsets in thymus, mesenteric lymph nodes and Peyer's patches of mice orally inoculated with T-2 toxin.

Development of apoptosis and changes in lymphocyte subsets were examined mainly by flow cytometer in thymus, mesenteric lymph nodes and Peyer's patches of mice up to 24 hours after oral inoculation with T-2 toxin (10 mg/kg). T-2 toxin attacked Peyer's patches first, then mesenteric lymph nodes, and finally thymus in relation to the course of enteric absorption of orally inoculated T-2 toxin. The degree of lymphocyte apoptosis was prominent in the thymus, moderate in the Peyer's patches, and somewhat mild in the mesenteric lymph nodes, suggesting the difference in lymphocyte population susceptible to T-2 toxin. As to the changes in lymphocyte subsets, CD4+ CD8+ T cells were most sensitive to T-2 toxin, and CD4+ CD8- T cells were more severely depressed than CD4- CD8+ T cells in the thymus. In the mesenteric lymph nodes, CD3+ cells was more clearly affected than CD19+ cells, and the numbers of CD4+ and CD8+ cells were similarly decreased. In the Peyer's patches, the numbers of CD3+, CD 19+, CD4+ and CD8+ cells were unexceptionally decreased. In addition, among IgM+, IgG+ and IgA+ B cells, the number of IA+ B cells which are more important in the mucosal immunity was most severely affected.