[The role of the structural components of bacterial lipopolysaccharide in its inductive immunosuppressive activity].

The inductive immunosuppressive activity of lipopolysaccharides (LPS) and structural parts (O-chains,cor,lipid A) obtained from bacteria of the genus Shigella and Escherichia coli was studied. LPS preparations were extracted by phenol-water method. Its structural components were obtained by the acetic acid hydrolysis and gel filtration. It has been shown that all these preparations did not change the level of delayed type hypersensitivity (DTH) to test-antigen in mice in the case of intraperitoneal injection. They did not also induce immunosuppressive activity in avirulent bacterial strains. After the redox treatment all LPS preparations acquired the ability to induce immunosuppressive property in avirulent bacteria. As a result of redox treatment the immunosuppressive activity appeared in lipid A preparations. O-chains and cor preparations were not active. Immunosuppressive activity was lost after treatment with phenol. It is supposed that active chemical groups are located in lipid A.