Assessment of apoptosis occurring in spleen cells from nitrogen mustard-treated or gamma-irradiated mice

The short-term consequences on spleen cells of the intraperitoneal administ ration of nitrogen mustard (HN-2) to mice or of a whole-body gamma irradiat ion have been evaluated. Experiments were designed to assess the induction of apoptosis in spleen cells following exposure to these agents. The occurr ence of this type of cell death was analysed by several methods, in particu lar the quantification in the blood of phosphotidylserine-bearing micropart icles shed by apoptotic cells. In response to HN-2 or radiations, spleens u ndergo a rapid involution of their weight and cellularity. Ex vivo apoptosi s occurs within 24 hours in cultured lymphocytes in a. dos-dependent manner after both treatments. As compared with untreated controls, circulating mi croparticles increased 3-fold after the injection of 5 mg/kg of HN-2.