Abstract Human antibodies specific for meningococcal group B polysaccharide (Bsss) in both pooled and individual sera were examined in a radioactive antigen binding assay using purified, high specific activity, 3H-labeled polysaccharide. The assay was performed at both 4°C and 37°C, and the results were compared with those from an analogous group C polysaccharide (Csss) system. The amount of antibody needed to bind 35 to 45% of the 3H-labeled antigen was five times higher at 37°C as at 4°C in the Bsss system. In contrast, only 1.2 times as much antibody was required at 37°C as at 4°C in the group C system. Mouse monoclonal Bsss- and Csss-specific antibodies gave similar results. Excess unlabeled homologous polysaccharide added to the Bsss system at equilibrium caused a rate of release of labeled polysaccharide antigen from antibody twice as high as in the group C system. No significant difference was observed when either purified or "native" (outer membrane-associated) polysaccharide was used as the unlabeled antigen. The above results indicated that the Bsss antibodies were of lower avidity than the Csss antibodies at 37°C. The similarity in the amount of competition by the purified and "native" polysaccharides suggested the antigenicity of the Bsss was not significantly altered during purification. Purified polysaccharides covalently bound to poly-L-lysine were used as antigen in a solid-phase radioimmunoassay to determine equilibrium binding constants of the human antibodies and mouse monoclonal antibodies. At 37°C, human anti-Csss antibodies had a binding constant 10 to 28 times higher than human "natural," convalescent, or post-vaccination anti-Bsss antibodies. The mouse monoclonal anti-Csss antibody had a binding constant 20 times higher than the anti-Bsss monoclonal antibody at 37°C.

Mandrell, R. E., & Zollinger, W. D. (1982). Measurement of antibodies to meningococcal group B polysaccharide: low avidity binding and equilibrium binding constants. The Journal of Immunology, 129(5), 2172–2178.