Secretion of IL-6, monocyte chemoattractant protein-1, macrophage inflammatory protein-1 alpha, and TNF alpha by cultured intact human peritoneum

The peritoneum is an important site of host defence. The mesothelial cells, lining the peritoneum, and the fibroblasts found in the layers below are p otent sources of a variety of mediators. Furthermore, granulocytes, mast ce lls, and macrophages, either resident or attracted by inflammatory processe s, are interspersed within the tissue. We investigated the production of me diators by samples of fresh human peritoneum. The method described here has the advantage that the cellular composition of the human peritoneum remain s intact. Samples of peritoneum were excised at the beginning of elective a bdominal operations in infection-free patients. The tissue was placed acros s the wells of a microtitre plate, fixed in place by the plate cover and in cubated with culture medium with or without lipopolysaccharide (LPS) for up to 5 h. The accumulation of IL-6, monocyte chemoattractant protein-1 (MCP- 1), macrophage inflammatory protein-1 alpha (MIP-1 alpha) and TNF alpha in culture supernatants was measured by ELISA. Production of MCP-1 and IL-6 oc curred spontaneously during incubation and was enhanced by as much as 4-fol d in the presence of different concentrations of LPS (0.5-500 ng/ml) in a d ose-dependent manner. MIP-1 alpha and TNF alpha were detected in culture su pernatants of LPS-stimulated samples with concentrations about 8 times as h igh as those of samples cultured with no such stimulus. The addition of IL- 1 beta resulted in an increase in the release of IL-6 and MCP-1, similar to that observed with LPS stimulation, but failed to increase the production of TNF alpha. MIP-1 alpha production was only marginally enhanced by IL-1 b eta In conclusion, our experimental system is suitable for the investigatio n of chemokine and cytokine production by the human peritoneum, with the ai m of assessing aspects of local immunocompetence.