Mild alkaline hydrolysis of lipopolysaccharide endotoxin enhances its mitogencity for murine B cells

Mild alkaline hydrolysis was found to enhance the mitogenicity of lipopolysaccharide endotoxin for murine B lymphocytes. Alkaline treated lipopolysaccharide also retained its property as a polyclonal activator. Whereas this treatment reduced the lethality of endotoxin for mice, its toxicity for lymphocytes cultured in the absence of fetal calf serum was increased. Lipid analysis indicated that there were no significant changes in the fatty acids of lipid A, but particle size was significantly reduced and the material was more homogeneous and soluble than untreated lipopolysaccharide. The relationship of these effect on the structure of lipopolysaccharide endotoxin to the mechanism of B-lymphocyte activation is discussed.