The influence of elevated fibronectin levels during sepsis on the distribution of blood-borne particles.

We assessed serum fibronectin levels during septic shock and modification of the levels by intravenous fibronectin infusion. Male rats subjected to cecal ligation and puncture received intravenously, either fibronectin in saline or saline only, 18-20 hours after the cecal ligation. The cecum was then excised. Fibronectin was assessed by electroimmunoassay and RES function by organ localization of gelatinized labeled colloid. Serum fibronectin concentration increased after the cecal ligation. It then fell one hour after the second operation (cecectomy) in saline-treated rats, but increased in fibronectin-treated rats. Fibronectin treatment did not enhance survival. Two other groups of rats received gelatinized labeled colloid one hour after the cecectomy. The fibronectin-treated group did not have increased hepatic uptake, but had increased pulmonary localization of gelatinized labeled colloid. The enhanced pulmonary localization may be due to fibronectin-induced opsonization and aggregation of particles which then embolize in the lungs. Though reversal of fibronectin deficiency has been documented to improve organ function, indiscriminate fibronectin supplementation without documentation of fibronectin deficiency should not be undertaken, since our present study demonstrates that excessive fibronectin levels may lead to particle aggregation.