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 gui nea pigs that were given an intravenous injection of Sephadex and its corre lation with markers of the development of inflammation. Materials and Methods: Dunkin Hartley guinea pigs (250-300 g) were used. Wh ole blood was collected by heart puncture in a sodium citrate solution (0.3 15 g/ml) for complement measurements. Complement activation was measured us ing a colorimetric haemolytic assay. Bronchoalveolar lavages (BAL) were per formed to monitor cell infiltration and inflammation was monitored by measu rements of eosinophil peroxidase (EPO), histamine, beta-glucuronidase, albu min and total proteins in the BAL fluid. Treatment: Guinea pigs were pre-treated with aprotinin (40 000 IKU/kg) 30 m in 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-Sep hadex and aprotinin reduced the blood complement activation and eosinophil infiltration/activation observed. Conclusions: Our results strongly suggest that complement is involved in th e cascade of events leading to the inflammatory state observed in guinea pi g following the intravenous injection of Sephadex beads.