[A new immunoluminometric solid phase sandwich assay for antibodies to hepatitis B surface antigen]

A solid phase quantitative immunoluminometric assay for antibodies to hepatitis B surface antigen (Anti-HBsAg) is described. This solid phase assay uses polystyrene balls of 6.4 mm diameter, coated with pure hepatitis B surface antigen (HBsAg) obtained from the plasma of chronic HBsAg carriers. After incubation with patient serum (90 min), HBsAg labelled with 7-(4-aminobutyl-N-ethyl)naphthalene 1,2-dicarboxylic acid hydrazide hemisuccinamide (ABEN-H) was used as the signal carrier. Dilutions of samples and standards were made with sera previously shown to be negative for anti HBsAg. The lower detection limit was about 1.3 U/l the upper limit for undiluted serum about 1000 U/l. The mean coefficient of variation was 5%. The dynamic range (expressed as the signal ratio of the highest standard: zero standard) was 182:1 and covered the range 23-4200 relative light units. The assay was tested for specificity and gave no false-positive reactions in the presence of other hepatitis B antigens and antibodies.