Computer aided analysis of antigen-antibody reactions

Antibodies are large molecules which are formed in the body to render antigens (causes of diseases) harmless. Bivalent antibodies and multivalent antigens may form a rich variety of different antigen-antibody complexes. The outcome of a reaction between an antigen and its antibodies can be analyzed experimentally by use of a gradient centrifugation technique.We have used computer models to study the extent to which the outcome of an antigen-antibody reaction is predictable from simple assumptions.First, a mathematical model for simulation of this particular centrifugal technique was constructed, allowing calculation of where in the centrifuge rotor a given complex would be located following centrifugation under precisely defined circumstances. Second, a program to predict the outcome of reactions between antigens and antibodies was written, based on the assumption that the kinds and the amounts of antigen-antibody complexes are determined by the concentrations of antigens and antibodies, respectively, together with a parameter describing their mutual affinity. Third, these programs were combined so as to calculate the expected outcome of antigen-antibody reactions as they appear after this type of centrifugal analysis. Finally, calculated results were compared to experimentally obtained results, and a fairly good agreement was found.It is concluded that the main characteristical features of such reactions are predictable from the above mentioned assumptions by use of these computer models.