Separation of the mitogenic and antigenic responses to bacterial lipopolysaccharide.

An attempt was made to separate the antigenic and mitogenic properties of E. coli bacteria and bacterial lipopolysaccharide antigen inhibited the mitogenic response by the cultures but did not inhibit the induction of anti-LPS antibody or polyclonal antibody synthesis to SRBC. Dextran sulphate, acting as a B-cell mitogen, increased the mitogenic response in spleen cell cultures incubated with bacteria, but did not affect the production of anti-LPS antibody. Mild alkaline hydrolysis (0-1 N NaOH at 56 degrees) of LPS destroyed the mitogenic properties of the molecule, leaving the antigenic properties qualitatively intact. Harsher conditions of base hydrolysis destroyed both the mitogenic and antigenic properties of LPS, as determined by antigenicity in murine spleen cell cultures and haemagglutination inhibition tests.