Plasma interleukin-18 levels in chronic renal failure and continuous ambulatory peritoneal dialysis

Background/Aims: Based on associations of interleukin (IL)-18 with chronic inflammation, we investigated IL-18, IL-6, and tumor necrosis factor-α (TNF-α) in patients with chronic renal failure (CRF) and patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Methods: Plasma was evaluated by ELISA methodology in 15 healthy controls, 27 CRF and 15 CAPD patients. Results: Plasma IL-18 levels in CRF (572.5 ± 41.9 pg/ml) or CAPD (479.2 ± 47.4 pg/ml) were significantly higher than normal (263.6 ± 20.0 pg/ml), but there was no difference in IL-18 between CRF and CAPD patients. The IL-18 concentration negatively correlated with creatinine clearance (Ccr). However, the duration of dialysis, normalized protein nitrogen appearance, weekly Ccr, and K_t/V_urea were not correlated with plasma IL-18 in CAPD. The plasma IL-18 concentration was positively correlated with TNF-α but not with IL-6 in renal failure patients with or without CAPD. Conclusion: Uremia is the principal origin of increased plasma IL-18 in these patients. Increased IL-18 levels may be associated with Th1 differentiation and elevated TNF-α.