Interaction between endotoxic lipopolysaccharides (LPS) and the complement (C) system: solubilization of C-consuming substances during brief absorbtions at 0 degrees.

Abstract

SummaryAttempts were made to remove antibodies and other serum factors involved in the interaction between endotoxic lipopolysaccharides (LPS) and the complement system by brief absorbtions of guinea pig serum with LPS at 0°. However, in addition to removal of serum factors, this procedure also resulted in the solubilization or “imbibation” of LPS constituents into the fluid phase, such that when the absorbed sera were subsequently incubated at 37°, or hyperimmune rabbit anti-LPS serum was added to them at either 0 or 37°, LPS constitutents which initiated C consumption were found. C consumption upon addition of LPS to absorbed sera persisted, even as bactericidal activity against the parent Veillonella organisms was reduced. While the importance of solubilization of LPS to its interaction with the C system is not yet known, these experiments show the difficulty of evaluating the factors in serum which initiate C consumption upon addition of LPS and their relationship to “natural” bactericidal antibodies.