Evidence for the activation of blood complement in Sephadex beads-induced lung inflammation in guinea pigs

OBJECTIVE AND DESIGN: This study evaluated the complement activation in guinea pigs that were given an intravenous injection of Sephadex and its correlation with markers of the development of inflammation. MATERIALS AND METHODS: Dunkin Hartley guinea pigs (250-300 g) were used. Whole blood was collected by heart puncture in a sodium citrate solution (0.315 g/ml) for complement measurements. Complement activation was measured using a colorimetric haemolytic assay. Bronchoalveolar lavages (BAL) were performed to monitor cell infiltration and inflammation was monitored by measurements of eosinophil peroxidase (EPO), histamine, beta-glucuronidase, albumin and total proteins in the BAL fluid. TREATMENT: Guinea pigs were pre-treated with aprotinin (40000 IKU/kg) 30 min before they were given an intravenous injection of Sephadex beads (24 mg/kg). Carboxymethyl (CM)-Sephadex (24 mg/kg) was administered alone. RESULTS: Sephadex beads activated the complement system in vitro (14.12+/-2.29 U/ml) and in vivo (9.95+/-0.08 U/ml) reaching a peak 6 h after the injection. This activation was accompanied by other characteristic features of inflammation such as leukocyte infiltration and activation. Both CM-Sephadex and aprotinin reduced the blood complement activation and eosinophil infiltration/activation observed. CONCLUSIONS: Our results strongly suggest that complement is involved in the cascade of events leading to the inflammatory state observed in guinea pig following the intravenous injection of Sephadex beads.