Reticuloendothelial failure in chronic intra-abdominal sepsis: the role of opsonic fibronectin

Severe sepsis leads to depression of the reticuloendothelial (RE) system with delayed bloodstream clearance of particulate matter and bacteria. Fibronectin may be an important opsonin of the RE system and low fibronectin levels often accompany severe sepsis in man. We have investigated the effect of prolonged intra-abdominal sepsis on plasma fibronectin concentrations and RE function. Serial plasma fibronectin concentrations were determined in rabbits for 2 weeks after either the induction of sepsis (appendix abscess) (n = 6) or laparotomy only (n = 6). RE function was measured at 2 weeks by determining the clearance kinetics and organ distribution of low dose technetium tin colloid (TTC). There was an early transient depression in plasma fibronectin values followed by elevated concentrations at 48-72 h which were more marked in the sepsis group. There was a delay in the blood clearance with reduced hepatic and increased bone uptake of TTC. We conclude that depletion of opsonic fibronectin is unlikely to be an important factor contributing to the impairment of RE function associated with intra-abdominal sepsis and that RE depression in septic animals is due to intrinsic Kupffer cell dysfunction.