[Enzyme linked immunosorbent assay for characterization of affinity and epitope specificity of antibodies to a polysaccharide antigen]. / Immunofermentnyi metod kharakteristiki antitel k polisakharidnomu antigenu po ikh affinosti i épitopnoi spetsifichnosti.

The use of the Langmuir equation for processing ELISA data (the sandwich variant) helped to ascribe a physical sense to the parameters of the optimization of the antigen-antibody titration curve: the maximum response that characterizes complete binding corresponds to the saturation of all epitopes of the antigen, and the concentration at which half of the maximum response is attained corresponds to the dissociation constant of the immune complex, i.e., to the average affinity of the antibodies. The algorithm was tested for systems in which antibodies against IgE and IgD were sorbed on a support, and the antigen bound was determined by the antibodies conjugated with peroxidase. A good fit of the experimental and theoretical curves and reasonable values for the affinity constants were found. In another system, the binding of specific IgG, IgM, and IgA antibodies with the polysaccharide from Neisseria meningitidis serotype A was studied during vaccine testing. The structural simplicity of the antigen molecule made it possible to suggest the presence of two main epitopes and to reveal the dynamics of formation of the antibodies to them.