Calculation of average antibody affinity in anti-hapten sera from data obtained by competitive radioimmunoassay.

A method is described for rapid and precise determination of average antibody affinity in anti-hapten sera from the following data obtained by competitive radioimmunoassay (RIA): the molar hapten (inhibitor) concentration giving 50% inhibition of tracer-antibody binding under equilibrium conditions, the molar tracer concentration in the assay and the amount of tracer bound by the antibodies in the absence of inhibitor. Thus, no additional experiments are required once a competitive RIA has been established. As an example, the average antibody affinity constants for 2'-deoxyguanosine, O6-ethyl-guanosine, and O6-ethyl-2'-deoxyguanosine were determined in antisera raised against the respective nucleoside-protein conjugates.