Immunohistochemical detection of endotoxin in endotoxemic rats.
BACKGROUND/AIMS: Although there are various methods to detect endotoxin mainly after the intravenous injection of purified endotoxin in a host, its uptake and distribution among the various organs is not well understood. In the present study, the time course of the distribution and disappearance of endotoxin in various rat organs following injection via two different routes was evaluated by an immunohistochemical staining method using a newly developed monoclonal antibody against Factor C. MATERIALS AND METHODS: The time course of the distribution of lipopolysaccharide (LPS) into the liver, spleen, lung, and kidney after intravenous (i.v.) or intraperitoneal (i.p.) injection of LPS was studied by immunohistochemical staining using a newly developed monoclonal antibody against Factor C in rats. Moreover, plasma endotoxin levels were measured by a modification of a chromogenic endotoxin-specific assay. RESULTS: At 30 minutes after injection in the i.v. group and at 12 and 24 hours in the i.p. group, endotoxin was present on Kupffer cells by staining and on some sinusoidal endothelial cells in the liver as well as on macrophages in the marginal zone of the spleen. The plasma endotoxin levels in the i.v. group decreased gradually after injection. However, levels in the i.p. group gradually increased, reaching a maximum level at 6 hours after injection, and then gradually decreasing. CONCLUSION: These results suggest that, regardless of the route of injection, endotoxin can be detected by an immunohistochemical staining method using a monoclonal antibody against Factor C.