Mitogenicity of Bacterial Endotoxins: Characterization of the Mitogenic Principle

Abstract

Endotoxins from smooth strains of Salmonella typhimurium and from rough variants of Ra, Rc and Re chemotype were mitogenic for mouse spleen cells. Haptenic polysaccharides and native protoplasmic polysaccharides possessed very little mitogenicity. Lipid A was strongly mitogenic. Mild alkaline hydrolysis of complete endotoxin or lipid A, a procedure which cleaves off ester-linked fatty acids, caused a substantial loss of mitogenic activity. These data indicate that endotoxin acts as a nonspecific or general mitogen and that the mitogenic response is not mediated by immunologic mechanisms.