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 verru carin A, and a non-macrocyclic trichothecene, T-2 toxin, on the concan avalin A-induced murine T-cell blastogenesis was investigated. The mac rocyclic trichothecenes inhibited the blastogenesis of both thymocytes and splenocytes, splenocytes being more resistant than thymocytes. Su ch resistance to macrocyclic trichothecenes was not observed in spleni c T-cells separated from the other cell population, nor in splenocytes depleted of adherent cells. In order to fmd the cell population respo nsible for resistance, the toxins were incubated with fractionated spl enic cells and then cytotoxicity of the supernatants of the incubation mixtures was examined by using T-cell blastogenesis assay. The result s showed that the splenocytes depleted of Ia-negative cells had the ab ility to reduce the cytotoxicity of the macrocyclic trichothecenes, bu t not that of T-2.