DIFFERENTIAL INDUCTION OF PROGRAMMED CELL-DEATH IN CD8(-CELLS BY THE B-SUBUNIT OF CHOLERA-TOXIN() AND CD4(+) T)

We have recently demonstrated that a short-term treatment of parental splenocytes with the B subunit of cholera toxin (CT-B) abrogates the d evelopment of acute GVHD in Fl hybrid mice transplanted with these cel ls. In order to obtain better insight into the mechanism of the action of CT-B, we studied the effect of CT-B on survival of purified murine T cells and their subsets. We show that treatment with B subunit stim ulates apoptosis in T cells, detectable following incubation in vitro. Although apoptosis was noticed in both CD8(+) and CD4(+) T cell subse ts, the treatment preferentially stimulates programmed cell death (PCD ) in CD8(+) population. Thus, immunosuppressive action of CT-B in vivo may be in part due to its ability to eliminate CD8(+) T cells. (C) 19 96 Academic Press, Inc.