Solid-phase radioimmunoassay with protein-A-bearing Staphylococcus aureus cells used to assay a protein (ferritin) and a hapten (digoxin).

Abstract We compared use of protein-A-containing Staphylococcus aureus bacteria with conventional ammonium sulfate precipitation and second-antibody methods of separating bound and free antigen in the radioimmunoassay of a hapten (digoxin) and protein (ferritin) in human sera. In each case, values obtained with the heat-killed, formalin-fixed bacteria correlated well with those found by established methods. No matrix effects …