Induction of apoptosis in murione spleen lymphocytes using carbon ion beam

To assess the capacity of heavy ions to induce apoptosis in lymphocytes, mi ce have been irradiated with accelerated carbon ions (95 MeV/nucleon) at do ses ranging from 0.1 to 4 Gy. Their spleens were removed 24 h later and gen tly dissociated to prepare a single cell suspension. Mononuclear cells were then maintained in culture at 37 degreesC, and the occurrence of apoptosis in these cells was analysed 24 h later. Lymphocytes were also irradiated i n vitro, in the presence of Ac-DEVD-CHO, a potent caspase-3 and -7 inhibito r. Results from three experiments performed at the Grand Accelerateur Natio nal d'Ions Lourds (GANIL, Caen, France) are reported here. They indicate th at carbon ions induce a marked, dose-dependent, reduction of the spleen wei ght and cellularity. However, in sharp contrast with spleen cells prepared from X-ray irradiated mice, only a slight increase of apoptosis is evidence d in cultured lymphocytes from mice irradiated with heavy ions. The signifi cance of such results is discussed. So far, few data exist concerning the b iological effects of heavy ions, in particular their capacity to induce apo ptosis in lymphocytes; the present study provides useful clues for further investigations.