BACKGROUNDLipopolysaccharide (LPS), the major glycolipid component of Gram-negative bacterial outer membranes, is a potent endotoxin responsible for many of the directly or indirectly induced symptoms of infection. Lipoproteins (in particular, high-density lipoproteins) sequester LPS, thereby acting as a humoral detoxification mechanism. PATIENTSDifferences in the lipoprotein composition in human plasma and lymph of a control patient group (n = 5) without systemic inflammatory response syndrome (non-SIRS/MOF) and patients with SIRS and multiple organ failure (MOF, n = 9) were studied. The LPS binding capacity of the lipoproteins in SIRS/MOF and non-SIRS/MOF patients was investigated by rechallenge of the plasma and lymph with fluorescently labeled LPS ex vivo. The lipoprotein composition was analyzed using immunochemical techniques and high-performance gel permeation chromatography. RESULTSIn the non-SIRS/MOF patient group, plasma and lymph levels of apolipoprotein A-I (600 and 450 mg/L, respectively), apolipoprotein B (440 and 280 mg/L, respectively), total cholesterol (2.88 and 1.05 mM, respectively), and total triglycerides (0.67 and 0.97 mM, respectively) were observed. In the SIRS/MOF group, a decrease of apolipoprotein A-I (−55% in plasma and lymph), a decrease of apolipoprotein B (−43% in plasma and −38% in lymph), and a decrease of total cholesterol levels (−54% in plasma and −37% in lymph) were demonstrated. However, the triglyceride levels in the SIRS/MOF group showed a 30% increase in plasma and a 47% decrease in lymph compared with the non-SIRS/MOF patients. In SIRS/MOF patients, a 2.8-fold increase in plasma and a 1.8-fold increase in lymph of the LPS low-density lipoprotein/high-density lipoprotein ratio was observed, indicating that the relative LPS binding capacity of the lipoproteins in the SIRS/MOF patient group showed a trend to be shifted mainly toward low-density lipoproteins. Furthermore, in plasma and lymph of four SIRS/MOF patients, a novel cholesterol-containing high-density lipoprotein–like particle was found that barely had LPS binding capacity (<5%). CONCLUSIONSIn the SIRS/MOF patients, the changes in lipoprotein composition in lymph are a reflection of those in plasma, except for the triglyceride levels. In comparison with the non-SIRS/MOF patients, the SIRS/MOF patients show a shifted LPS binding capacity of high-density lipoproteins toward low-density lipoproteins in plasma and in lymph. Moreover, in plasma and lymph, novel cholesterol-containing particles, resembling high-density lipoprotein, were identified in the SIRS/MOF patient group.