[Immunosuppressive components of extracellular polysaccharide from Pseudomonas aeruginosa clinical strains]

The immunosuppressive activity of lipopolysaccharide (LPS) contained in filtrates of newly isolated P. aeruginosa cultures was studied. The experimental model of delayed hypersensitivity to non-bacterial antigen in CBA mice and gel filtration through Sephadex G-200 were used. In addition to the already known LPS component with direct immunosuppressive action and having a mol.wt. of 150-800 kD, a new component was detected. It was found to be in inactive state and could be activated by redox treatment, thus becoming capable of inducing capacity for immunosuppression in Escherichia coli. This component had a mol.wt. of 50-70 kD and lost its activity after heating.