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 administration of nitrogen mustard (HN-2) to mice or of a whole-body gamma irradiation have been evaluated. Experiments were designed to assess the induction of apoptosis in spleen cells following exposure to these agents. The occurrence of this type of cell death was analysed by several methods, in particular the quantification in the blood of phosphotidylserine-bearing microparticles shed by apoptotic cells. In response to HN-2 or radiations, spleens undergo a rapid involution of their weight and cellularity. Ex vivo apoptosis occurs within 24 hours in cultured lymphocytes in a dose-dependent manner after both treatments. As compared with untreated controls, circulating microparticles increased 3-fold after the injection of 5 mg/kg of HN-2.