Measurement of antigen - antibody binding constants by elution of affinity chromatography columns with continuous concentration gradients of dissociating agents

Elution of antibody-Sepharose 4 B columns previously loaded with antigen by a linear concentration gradient of Na I or NaSCN, was used for the calculation of binding constants for the human IgG - anti human IgG system. The values obtained by this method showed good agreement with the values obtained by " stepwise" elution with different NaI concen - trations, with the values obtained when the antigen was immobilized, and with the values determined in solution. The method employed appears as a simple and useful possibility for the determination or comparison of K values.