Standardization of the antibody to hepatitis B surface antigen concentration

We examine sources of potential bias in the estimation of antibody to hepatitis B surface antigen concentrations by a calibration curve for conversion of RIA units to international units. We show by calculation and example that very large biases may exist, whereas accurate estimation is needed in screening programmes and in clinical trials for the evaluation of the immunogenicity of various types and schedules of hepatitis B vaccine. It is recommended that the danger of large biases be avoided by using the laboratory's own calibration curve, calibrated against dilutions of the WHO standard, using a standard as positive control in the radioimmunoassay. Furthermore, serum samples should be diluted to a concentration close to that of the positive control.