Release of endotoxin-binding proteins during major elective surgery: Role of soluble CD14 in phagocytic activation

Our previous study demonstrated that soluble CD14 (sCD14) modulates the bio logic activity of circulating endotoxin, which appears after surgery. In th is study, we examined the behavior of endotoxin-binding proteins, such as s CD14, lipopolysaccharide-binding protein (LBP), and bactericidal/permeabili ty-increasing protein (BPI), in patients' plasma after major abdominal surg ery and the phagocytic secretion of sCD14 from peripheral blood mononuclear cells (PBMCs) throughout the observation period. In a prospective study, 1 5 patients undergoing major abdominal surgery (gastrectomy, n = 3; pancreat ectomy, n = 10; colectomy, n = 2) were involved in this study. The endotoxi n-binding proteins were perioperatively (preoperatively; postoperative hour 6; days 1, 2, 3, 4, 5, 7, and 10) measured by an enzyme-linked immunosorbe nt assay (ELISA). To exclude the hemodilution effect of samples, each param eter was corrected by dividing the respective value by the albumin concentr ation. The phagocytic activity at each time point was tested as an ex vivo sCD14 secretion from PBMCs in the presence and absence of exogenously added endotoxin, Escherichia coli 055B5 (1 ng/ml). Significant endotoxemia (0.35 +/- 0.13 EU/ml; p < 0.05) was observed 6 hours after the beginning of surg ery. The sCD14/albumin value rapidly increased at 6 hours after surgery, pe aked on day 1, and sequentially declined, whereas the BPI/albumin and LBP/a lbumin ratios increased more gradually and peaked on day 2. The secretion o f sCD14 from 2 x 10(6) PBMCs was significantly enhanced from 6 hours after operation. The increased plasma level of sCD14 may be explained by the para llel-enhanced sCD14 PBMC production. Activated secretion of these endotoxin -binding proteins may play a role in regulating the biologic activity of ci rculating endotoxin.