Differential Induction of Programmed Cell Death in CD8+and CD4+T Cells by the B Subunit of Cholera Toxin

We have recently demonstrated that a short-term treatment of parental splenocytes with the B subunit of cholera toxin (CT-B) abrogates the development of acute GVHD in F1 hybrid mice transplanted with these cells. 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 stimulates apoptosis in T cells, detectable following incubationin vitro.Although apoptosis was noticed in both CD8+and CD4+T cell subsets, the treatment preferentially stimulates programmed cell death (PCD) in CD8+population. Thus, immunosuppressive action of CT-Bin vivomay be in part due to its ability to eliminate CD8+T cells.