Labeling of Rh antibodies on solid-phase protein A

Rh0(D) antibodies which retain immune specificity after radiolabeling were prepared by a procedure which does not require IgG isolation from serum, requires 10-fold less isotope than conventional techniques and yields antibody solutions of defined composition. The method involves radioiodination of IgG on immobilized protein A, depends on employing human red cells reduced in surface cytophilic IgG, and exploits the inability of goat IgG to interact with Staphylococcus aureus protein A. The technique concentrates IgG by affinity adsorption and should prove useful in preparing radiolabeled alloantibodies from dilute human antisera and for red cell autoantibodies.