LIPOPOLYSACCHARIDE-BINDING PROTEIN IS PRESENT IN EFFLUENTS OF PATIENTS WITH GRAM-NEGATIVE AND GRAM-POSITIVE CAPD PERITONITIS

Background. Bacterial peritonitis is a frequent complication during tr eatment of end-stage renal failure by continuous ambulatory peritoneal dialysis. Local host defence mechanisms including the secretion of pr oinflammatory cytokines by peritoneal macrophages are of particular im portance in the pathogenesis of infectious complications. LPS-binding protein (LBP) and soluble CD14 (sCD14) are serum factors known to regu late the endotoxin-induced cellular immune response. However, it is st ill unknown whether LBP and sCD14 are also present in the peritoneal e ffluent of CAPD patients. Methods. Using specific immunoassays, we exa mined the concentration of LBP, sCD14 and the proinflammatory cytokine s TNF-alpha, IL-1 beta and IL-6 in the dialysis effluents of 31 patien ts with CAPD-associated peritonitis. Twenty patients without peritonit is served as controls. Intraperitoneal LPS concentrations were determi ned using the limulus amebocyte lysate assay. Results. Bacterial lipop olysaccharide could be detected in 42% of the infected dialysis efflue nts. In comparison to controls (0.2+/-0.05 mu g/ml), LBP was significa ntly elevated in both Gram-negative/LPS-positive (1.03+/- 0.3 mu g/ml) and Gram-positive infections (0.5+/- 0.14 mu g/ml) (P<0.05). No signi ficant differences were detected concerning the intraperitoneal sCD14 levels in the three patient groups. Levels of TNF-alpha, IL-1 beta and IL-6 were significantly increased in the effluents of patients with b acterial peritonitis compared to noninfected controls. Moreover the re spective cytokine concentrations were significantly higher in the Gram -negative/LPS-positive compared to the Gram-positive bacterial infecti ons (P<0.01). Conclusion. Our data demonstrate that LBP is significant ly elevated in the dialysis effluents of patients with CAPD-associated peritonitis caused by both Gram-negative and Gram-positive bacteria a nd might be used as a marker of intraperitoneal infection. Moreover, o ur findings support the concept that LBP enhances the effects of LPS o n cytokine production by peritoneal macrophages. The function of LBP i n Gram-positive infection remains to be further elucidated.