Reisolation of immunoreactive radioiodinated antigens using glutaraldehyde-insolubilized antibody preparations.

Radioiodination of antigens for use in radioimmunoassay can result in substantial losses of antigenic reactivity with the corresponding antibody and antisera preparations. We describe a method whereby antigens iodinated with the chloramine-T procedure are bound to and eluted from glutaraldehyde-insolubilized antibody. Unfractionated antisera, an ammonium sulfate precipitated fraction or the IgG fraction of antisera may be used as insolubilized immunoadsorbents. The method has been applied for the reisolation of a radioiodinated peptide, a low molecular weight protein and the fibronectin molecule. The total binding of 125I-antigens to antibody in radioimmunoassays can be increased from such low amounts before reisolation that the assay is not feasible, to 85% above background binding, after adsorption and elution from the insolubilized antibody preparations.