Antibody-independent activation of the classical pathway of human serum complement by lipid A is restricted to Re-chemotype lipopolysaccharide and purified lipid A. Infect. Immun

Incubation of most bacterial lipopolysaccharides (LPS) with normal human sera at 37C activates the serum complement system, resulting in decreased levels of hemolytic complement. A Buffers. A variety of buffers containing isotonic sodium barbital-buffered (pH 7.35) saline (VBS) were used for these studies: GVB++, VBS with 0.1% gelatin-1.0 mM Mg2+-0.15 mM Ca2+; VBS-Mg2+-Ca2+, GVB++ without gelatin; VEM, VBS with 8 mM ethylene glycol-bis(,-aminoethyl ether)-N,N,N',N'-tetraacetic acid-2.0 mM Mg2+-0. 1% gelatin