The cytotoxicity of macrocyclic trichothecenes, roridin A and verrucarin A, on murine T-cells is reduced by Ia-negative splenic adherent cells.

The in vitro effect of macrocyclic trichothecenes, roridin A and verrucarin A, and a non-macrocyclic trichothecene, T-2 toxin, on the concanavalin A-induced murine T-cell blastogenesis was investigated. The macrocyclic trichothecenes inhibited the blastogenesis of both thymocytes and splenocytes, splenocytes being more resistant than thymocytes. Such resistance to macrocyclic trichothecenes was not observed in splenic T-cells separated from the other cell population, nor in splenocytes depleted of adherent cells. In order to find the cell population responsible for resistance, the toxins were incubated with fractionated splenic cells and then cytotoxicity of the supernatants of the incubation mixtures was examined by using T-cell blastogenesis assay. The results showed that the splenocytes depleted of Ia-negative cells had the ability to reduce the cytotoxicity of the macrocyclic trichothecenes, but not that of T-2.