title: Radioimmunoassay for the simultaneous detection and quantitation of hepatitis B surface antigen and of the homologous antibody.
abstract: A solid-phase radioimmunoassay procedure is presented, which allows the simultaneous detection and quantitation of HB, Ag and of anti-HBs. This procedure involves short preliminary incubation of test sera and of negative controls with a standard HB, Ag. The standard HBs Ag is diluted, according to preliminary assays, in order to yield a count ratio to negative controls of 10 to 1. Therefore, a value of 10 is ascribed to the counts of positive controls (standard HBs, Ag + HBs-negative serum) and counts of all test sera are proportionally related. The values obtained are denominated HBs Units. Test sera are considered to be positive for HBs Ag or anti-HBs when the corresponding HBs Units are significantly higher or lower, respectively, than the average value of standard antigen controls. Including the reference standard HBs Ag controls in each set of assays ensures the quantitative reproducibility of results among different assays and among different laboratories. Titres of serum HBs Ag and anti-HBs can be expressed as end-point dilutions, simply by plotting the corresponding HBs Units on a nomography. This was drawn according to the indications emerging from analysis of the radioimmunoassay kinetics. Laboratory assays and the practical application of the combined procedure over several thousands determinations showed that the binding capacity of the solid-phase substrate used (small antibody-coated polystyrene tubes) is extremely homogeneous. Such homogeneity accounts for a very high accuracy and reproducibility of quantitative results.
mesh_terms: D000906:Antibodies / Q000032:analysis*; D006510:Hepatitis B Antibodies / Q000032:analysis*; D006511:Hepatitis B Antigens / Q000032:analysis*; D011137:Polystyrenes; D011863:Radioimmunoassay / Q000379:methods; D011947:Receptors, Antigen, B-Cell / Q000032:analysis
chemical_list: D000906:Antibodies; D006510:Hepatitis B Antibodies; D006511:Hepatitis B Antigens; D011137:Polystyrenes; D011947:Receptors, Antigen, B-Cell