[The inductive immunosuppressive activity of the lipopolysaccharide from Shigella sonnei R forms].

Investigations have been carried out to find the position of lypopolysaccharide (LPS) structural part which can be activated by the redox system and to study peculiarities of its activation. Cell-free culture filtrate (CF) of Shigella sonnei strain R colonies on the nutrient agar medium was used. It was shown that CF contained three active fractions possessing inductive immunosuppressive properties. From all the phenol-water LPS fractions only lipid A possessed activity after redox treatment. O-chain and our fractions did not express such activity. The results of our investigations have shown that inductive immunosuppressive activity of the Shigella sonnei LPS was determined by lipid A.