Blood groups and susceptibility to gonococcal infection. II. The relationship of lipopolysaccharide type to gonococcal sensitivity to the bactericidal activity of normal human serum.

This study examines the bactericidal activity of normal human sera from individuals of blood groups A and B for gonococcal strains with simple and complex lipopolysaccharides (defined by pyocin-sensitivity) isolated from localised and disseminated infection. The bactericidal activity did not depend on A or B isohaemagglutinins. Resistance to normal human serum exhibited by strains from localised infections appeared to be due to lack of part of the lipopolysaccharide antigen, whereas resistance of strains from disseminated infection appeared to depend on a separate mechanism yet to be defined.