Antibody Responses of Mice to Alkaline Detoxified Lipopolysaccharide

The antibody responses of outbred normal mice and nude mice injected with alkaline detoxified lipopolysaccharide (Alk-LPS) were measured. In some cases the antibody responses to Alk-LPS were compared to responses made against lipopolysaccharide (LPS) and native protoplasmic polysaccharide (NPP). The kinetics of the primary responses to Alk-LPS and NPP were similar, whereas LPS stimulated a more rapid appearance of antibodies in the primary responses. Alk-LPS stimulated only primary antibody responses in both types of mice and sensitized nude mice for secondary responses which could be triggered with LPS. However, secondary antibody responses could not be triggered in normal mice primed with Alk-LPS. These data suggested that, on a functional basis, Alk-LPS possessed the specific antigenic signal associated with LPS antigens but lacked the second nonspecific mitogenic signal dependent on the lipid A portion of LPS.