The inhibitory effect of T-2 toxin on tolerance induction of delayed-type hypersensitivity in mice.

Mice injected intravenously with 1 X 10(9) sheep red blood cells (SRBC) showed no delayed-type hypersensitivity (DTH) response to SRBC and were unresponsive to DTH induction by sc injection of an optimal dose of SRBC. However, when treated with T-2 toxin, a mycotoxin, 2 days after the iv injection, mice became to show significant DTH response and to be responsive to the DTH induction by the sc injection. When the spleen cells of the mice receiving the iv injection were transferred to unsensitized syngeneic recipients, the DTH response of the recipients to SRBC was suppressed. However, the suppressor activity of the spleen cells was decreased by T-2 toxin treatment. By the iv injection, cell population of the spleen was increased and that of the thymus decreased. In contrast, by T-2 toxin treatment 2 days after the iv injection, cell population of the spleen was not increased and that of the thymus was markedly decreased. The ratio of theta-bearing cells was increased in the spleen by the iv injection. However, such increase was not observed after the T-2 toxin treatment. The ratio of Ig-bearing cells in the spleen was not changed by the iv injection and the T-2 toxin treatment after the iv injection. T-2 toxin seems to interfere with generation of suppressor cells for the DTH response.