title: Comparison of confirmation methods for hepatitis-B antigen and the nature of false-positives detected by 125I-immunoglobulins.
abstract: Immunologic specificity associated with solid-phase direct radioimmunoassay (RIA) using guinea pig antibodies for HBsAg detection (Ausria-125TM) was examined further with physicochemical techniques. The RIA reactivities which could not be neutralized by wide-spectrum human anti-HBs serum appeared to be physically distinct from true HBsAg particles; hence, they were truly false-positive, resulting from immunologic cross-reactions. In order to ensure the full advantages of using this highly sensitive RIA test, a confirmatory test using specific human anti-HBs for neutralization is therefore required to distinguish the true- and false-positives. The basic RIA technique is a two-step procedure. Two basic confirmation procedures, namely, a first-step neutralization and a second-step neutralization, were investigated in depth to assess their efficacy and practicality for confirmation. Both procedures were effective for confirmation purposes; however, the first-step neutralization procedure failed to confirm some high-titered HBsAg samples unless these samples were appropriately diluted. The second-step neutralization method did not require dilutions of any test samples.
mesh_terms: D000818:Animals; D000906:Antibodies; D000918:Antibody Specificity; D001782:Blood Donors; D003429:Cross Reactions; D005189:False Positive Reactions; D006168:Guinea Pigs / Q000276:immunology; D006511:Hepatitis B Antigens / Q000032:analysis*; D006801:Humans; D007136:Immunoglobulins; D007457:Iodine Radioisotopes; D009500:Neutralization Tests; D011863:Radioimmunoassay / Q000379:methods*
chemical_list: D000906:Antibodies; D006511:Hepatitis B Antigens; D007136:Immunoglobulins; D007457:Iodine Radioisotopes