Immunogenicity of gonococcal Gc2 polysaccharide: comparative studies with pneumococcal type III polysaccharide and Salmonella typhosa Vi antigen

A plaque assay technique was used to assess the immunogenicity of a gonococcal cell wall polysaccharide (Gc2 antigen) in BALB/c mice. The Gc2 antigen was shown to be immunogenic, and the kinetics of the response differed from that of a pneumococcal polysaccharide (SSS-III) and a polysaccharide antigen of Salmonella typhosa (Vi antigen). In addition, using antithymocyte sera, the T-lymphocyte dependency of these antigens was investigated. The immune response to the Gc2 antigen was demonstrated to be dependent on a population of helper T cells, whereas the response to SSS-III appears to be regulated by suppressor T cells. There appears to be marked differences in the immune response of mice to different bacterial polysaccharides.