Complement and leukocyte activation in septic baboons.

The effect of Escherichia coli infusion on complement and leukocytes was evaluated in a baboon model. During 8 hr, different amounts of live E. coli (5 x 10(8), 2.5 x 10(9) and 10(10) live bacteria kg body weight) were infused. Twenty-one baboons were investigated. Activation of complement (terminal C5b-9 complement complex; TCC) and activation of leukocytes (PMN elastase) and plasma concentrations of endotoxin (lipopolysaccharide; LPS) were determined before the start of bacteria infusion and 2, 4, 6, and 8 hr after the start of infusion. In baboons receiving 2.5 x 10(9) and 10(10) live E. coli per kilogram body weight, increasing plasma levels of TCC were found (P < 0.05). No significant alterations of TCC were observed when animals were infused with 5 x 10(8) live E. coli per kilogram body weight during an 8 hr period. Plasma levels of PMN elastase increased significantly in baboons receiving 5 x 10(8), 2.5 x 10(9), and 10(10) live bacteria per kilogram body weight. High levels of LPS were detected in animals receiving 10(10) live E. coli bacteria per kilogram body weight and in animals receiving 5 x 10(8) or 2.5 x 10(9) live E. coli bacteria per kilogram body weight. There was a positive correlation between the formation of TCC and the plasma levels of PMN elastase and LPS and between plasma levels of PMN elastase and of LPS. Activation of complement and leukocytes may contribute to the development of organ dysfunction seen in baboons infused with high amounts of live E. coli.