Adjuvant effect of lipid A obtained from Salmonella typhimurium on antibody response in mouse spleen. The role of carriers conjugated to lipid A

Immunological properties of Vibrio cholerae lipopolysaccharides

Immunological effects of wall lipopolysaccharide (LPS) preparations obtained from Vibrio cholerae Inaba 569B, Ogawa NIH 41 and NAG 4715 strains by the hot phenol-water procedure were examined in mice. Although these LPS lack KDO, which are basic components of the core region of most gram-negative LPS, they still have potencies as B-cell mitogens, adjuvants, immunosuppressants, polyclonal B-cell activators and phagocytic stimulants for macrophages. The activities of these V. cholerae LPS on murine immune system seemed to be weaker than those of Salmonella typhimurium LT2-LPS. Among these V. cholerae LPS, NAG 4715-LPS showed the strongest mitogenic activity and phagocytic stimulation, while the potencies of this NAG 4715-LPS for the induction of polyclonal B cell activation, adjuvant effects and immunosuppression did not seem to be greater to those of the other LPS.

Immunosuppressive effect of bacterial lipopolysaccharide on antibody response

Injection of endotoxins (bacterial lipopolysaccharide: LPS) several days prior to immunization causes the suppression of antibody response. The supressive effects of several kinds of LPS preparations on the plaque-forming cell (PFC) antibody response in the spleen of mice were examined after immunization with sheep red blood cells (SRBC). Glycolipids obtained from heptoseless mutants(Reform) of salmonella or its lipid A preparation coupled artificially with bovine serum albumin (BSA) are capable, like LPSobtained from a wild type (S form) strain, of inducing suppressionson of the PFC response, while alkaline-detoxified LPS can not. The refractory periods of the PFC response induced by LPS injection last only a few days. However, the use of cyclophosphamide (CY) together with LPS can extend the refractory periods of antigenic stimulation for several weeks. Injections of LPS andCY can also induce unresponsive states of OH agglutinin antibody response to antigenic stimulation with formalin-killed organisms of Escherichia coli or Salmonella enteritidis (presumably both thymus-independent antigens). These unresponsive states induced by LPS and CY are easily terminated by a transfer of syngeneic bone marrow cells but not by thymocyte transfer.