PLASMA-LIPID CONCENTRATIONS CORRELATE INVERSELY WITH CPB-INDUCED INTERLEUKIN-6 RELEASE

Purpose: Cardiopulmonary bypass (CPB) is characterized by translocatio n oi intestinal endotoxin and subsequent endogenous production of the pro-inflammatory cytokine interleukin-6, (IL-6), Plasma lipid fraction s, especially high density lipoproteins, bind and neutralize endotoxin and, therefore, inhibit endotoxin-induced macrophage cytokine product ion, including IL-6. increased IL-6 plasma levels have been implicated in adverse consequences associated with CPB. Previous studies demonst rated large interpatient variability in IL-6 plasma levels after CPB. The purpose of this study was to evaluate the relationship between pla sma lipid concentrations and the concentrations of IL-6 following CPB in humans, Methods: In a prospective study, a group of 15 patients sel ected to exclude variables known to influence post-CPB, plasma levels of IL-6 (preoperative left ventricular ejection fraction >45%, similar durations of aortic cross clamping and total CPB time, similar temper ature control during CPB, and avoidance of platelet transfusion and sh ed mediastinal blood re-infusion), IL-6 was measured at baseline, one and 24 hr post-CPB. Results: Interleukin-6 plasma concentrations (mean +/- SD) increased at one (142 +/- 89 pg.ml(-1), P < 0.05) and 24 (129 +/- 82 pg.ml(-1), P < 0.05) hr post-CPB compared with baseline(1.5 +/ - 1 pg.ml(-1)) concentrations, An inverse correlation was found betwee n IL-6 plasma concentrations at one hour post-CPB and plasma cholester ol concentrations (r = -0.592, P = 0.02), high density lipoprotein (r = -0.595, P = 0.02), and low density lipoprotein (r = -0.656, P = 0.01 ). Conclusions: These results suggest that plasma lipids attenuate the production of IL-6 during CPB and may partly explain the variability of interpatient levels of IL-6 reported post-CPB by others.