Lipopolysaccharide (LPS) injected intravenously produces leukopenia and sequestration of polymorphonuclear leukocytes (PMN) in the pulmonary vascular bed. To evaluate the role of complement in this process, we used C5-sufficient (B10.D2/nSn) and C5-deficient (B10.D2/oSn) mice and Sprague-Dawley rats depleted of complement with Naja naja cobra venom factor (CVF). We found a comparable increase in the number of PMN in lung tissue of C5-sufficient and C5-deficient mice given Escherichia coli LPS (0127:B8, 3 mg/kg), revealing that LPS acts independently of C5 and its biologically active fragments. Intravenous injection of LPS (3 mg/kg) into rats caused significant intravascular complement activation as assessed by serum CH50 and resulted in an almost 10-fold increase in numbers of PMN in lung tissue. Pretreatment of rats with CVF (50 U) did not reduce LPS-induced PMN sequestration, suggesting that the process is independent of C3. As reported previously, we found large numbers of PMN in bronchoalveolar lavage samples of rats 24 h after injection of LPS (3 mg/kg). Complement depletion did not prevent LPS-induced migration of PMN. No PMN migration occurred 2, 6, 12, 24, or 48 h after injection of CVF alone, indicating that complement activation is not sufficient to cause PMN migration. In contrast to our findings in rats, no PMN migrated into airspaces of C5-sufficient and C5-deficient mice 24 or 48 h after injection of LPS (3 to 20 mg/kg).
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine