The study of immunoaffinity purification of 125I-β HCG monoclonal antibody

Three labelling methods of β-HCG monoclone antibody have been compared by using Iodogen, N-Bromosuccinimide and Bolton-Hunter regents. The optimum method for protecting biological activity of antibody is the use of B-H reagent, and the biological activity can be damaged about 25% by labelling using other methods. The usefulness of immunoaffinity methods for the preparation of biologically fully active radiolabelled antibodies was investigated by using anti β-HCG as an example. The immunoaffinity purification increased the fraction of antigen binding antibody after previous labelling from 25% to 81% and also increased the radiochemical purity of antibody from 81% to 98%. Labelling in the antigenbound state offers the potential to protect the biologically active site from chemical or structural damage. This method seems particularly useful for the preparation of tracers for radioimmunoassays and radioimmunoimaging