Prodigiosin 25C: effect in in vitro models for T cell activation and T cell cycling and in vivo for rat heart allografts.

Prodigiosin 25C inhibited both lymphocyte activation (concanavalin-A-activated mouse spleen cells) and constitutive cell cycling of T cells and fibroblasts. This suggests that prodigiosin 25C is not selective for activation of T lymphocytes as has been previously reported. Use of prodigiosin 25C to suppress allograft rejection of rat hearts (DA to PVG) showed that 1 mg/kg/day i.p. had no effect whilst 10 mg/kg/day i.p. was toxic as manifest by weight loss and diarrhoea at 3 days. Although this toxicity was reversible upon reversion to 1 mg/kg/day, no major prolongation in allograft survival was seen. Our data suggests that prodigiosin 25C has a low therapeutic index and may not be selective for T cell activation.