THYMIC ATROPHY CAUSED BY THYMOCYTE APOPTOSIS IN EXPERIMENTAL SEVERE ACUTE-PANCREATITIS

Although a reduction in peripheral lymphocytes has been reported in cl inical cases of acute pancreatitis, the thymic change remains still un known. To investigate impairment of cellular immunity in acute pancrea titis, alterations of the thymus in rats with acute pancreatitis were examined experimentally. Male Wistar rats were used. Two groups with p ancreatitis of different severity and a control group for each were es tablished. The thymus was weighed and the number of thymocytes counted . Apoptosis in the thymus was examined by in situ nick-end labeling, D NA agarose gel electrophoresis, and cell cycle analysis using propidiu m iodide. Both thymus weight and number of thymocytes decreased signif icantly in the rats with necrotizing pancreatitis 20 h after induction of pancreatitis (P <0.02 vs sham operation). Neither thymus atrophy n or thymocyte reduction was observed in rats with edematous pancreatiti s. In thymuses from rats with necrotizing pancreatitis, in situ nick-e nd labeling showed a significant increase in apoptotic changes of thym ocytes, which was also confirmed by the stepladder pattern on agarose gel electrophoresis of the extracted DNA and by cell cycle analysis. I t is concluded that thymus atrophy associated with apoptosis occurs in rats with necrotizing pancreatitis. (C) 1998 Academic Press.