Toxic and immunological properties of the lipopolysaccharides (O-antigens) fromVibrio el-tor

Both lipopolysaccharides and lipid A moiety prepared fromVibrio el-tor exhibited almost equal endotoxic activities in eliciting the local Shwartzman reaction, in Limulus-lysate gelation, in chick-embryo lethality and pyrogenicity. The structural part responsible for these activities of lipopolysaccharides is the lipid A moiety. The high anti-complementary activities present in lipopolysaccharides and lipid A moiety was destroyed by alkaline digestion of the samples. Lipid A antiserum can protect against some of the toxic activities of the endotoxin in animals.