Effect of intraperitoneally administered plant lectins on leukocyte diapedesis and visceral organ weight in rats and mice

The effects of intraperitoneally administered plant lectins were examined in rats and mice. Intraperitoneally injected ConA transiently decreased the leukocyte count in the peritoneal cavity, due to the agglutination and attachment of cells to the peritoneal lining. Subsequently the total cell count was increased for hours, exceeding initial values. Peritoneal fluid aspartate transaminase (AST) concentration showed little change during the accumulation of ascitic fluid. The most marked histological alterations were found when wheat germ lectin was injected ip. (WGA, 10 mg/kg, 6 h). Neutrophil granulocytes migrated across the wall of both arterioles and venules, but the response was highly variable among adjacent vessels. The wall of the arterioles may have impeded the migration of neutrophil granulocytes, resulting in their accumulation in the muscular layer. Granulocyte accumulation was also observed in patches under the mesothelium and in other sites of the interstitium. Marked dilatation and thrombosis of a few venules were also observed. Kidney bean lectin (PHA) induced similar but less pronounced changes. The neutrophil diapedesis suggests the release of mediator(s) from mesothelial cells and/or peritoneal white cells. The cytokine-induced neutrophil chemoattractant CINC-1, injected as control, resulted in the diapedesis of predominantly mononuclear cells in the omentum within 40 minutes. In rats ip. injected ConA increased the wet weight of spleen and liver within 6 and 10 h, respectively, but kidney weight did not change. Intravascular clumping of red blood cells, thrombosis and organ weight changes also suggest the absorption of ConA into the circulation. The experiments show that plant lectins, used as models of bacterial lectins, can reproduce some aspects of peritonitis.