Further investigations on the affinity chromatography of unlabeled and labeled cortisol-binding immunoglobulin.

A specific method for the isolation of cortisol-binding immunoglobulin from rabbit antiserum by affinity chromatography on sepharose-coupled haptene (sepharose-cortisol) is described. This isolation technique has the advantage that no nonspecific gamma-globulin is present in the eluate of the column; previous absorption of anti-BSA-globulin can be omitted. The nature of the isolated immunoglobulin is determined by immuno-electrophoresis. The same isolation procedure can be used for the purification of radioactive antibody for radioimmunometric assay after labeling the immunoglobulin with iodine-125.