Differential induction of programmed cell death in CD8 super(+) and CD4 super(+) 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 incubation in vitro. Although apoptosis was noticed in both CD8 super(+) and CD4 super(+) T cell subsets, the treatment preferentially stimulates programmed cell death (PCD) in CD8 super(+) population. Thus, immunosuppressive action of CT-B in vivo may be in part due to its liability to eliminate CD8 super(+) T cells.