Peritoneal mesothelial cell injury factors in rat cancerous ascites.

To elucidate the mechanism of the peritoneal dissemination of cancer, the influence of cancerous ascites on peritoneal mesothelial cells was studied by scanning electron microscopy and light microscopy. We inoculated normal Donryu rats with AH100B ascites hepatoma cells and studied the influence of the supernatant from cancerous ascites on the normal rat peritoneal surface by i.p. injection. The mesothelial cells were damaged and exfoliated markedly, which is supposed to be a profitable condition for cancer cells to proliferate on the peritoneal surface. Therefore, the presence of mesothelial cell injury factors was noted. Subsequently, we divided the supernatant from rat cancerous ascites into four fractions by gel filtration and revealed the distribution of mesothelial cell injury factors by studying the influence of each fraction on the normal rat peritoneal surface. Although Fraction I (fibrin fraction) and Fraction II (IgG fraction) made no changes on the peritoneal surface, Fraction III (albumin fraction) and Fraction IV provoked damages on the mesothelial cells. We found that the mesothelial cell injury factors are present in the albumin fraction and in the fraction containing low-molecular-weight substances.