Comparative sensitivities of radioimmunoassay, crossoverelectrophoresis, and agar gel immunodiffusion for HBAg detection.

The relative sensitivities of radioimmunoassay, crossoverelectrophoresis, and agar gel immunodiffusion for detecting HBAg in unconcentrated versus concentrated serum samples are compared and discussed. The sensitivities of the various immunologic methods were enhanced severalfold in concentrated serum samples. This is a fundamental consideration in designing a screening program for detecting HBAg and anti-HBAg antibody in hospital patients and donors. The authors propose that serum samples that have marginal reactions or low counts (RIA) be concentrated with Lyphogel or MiniconTM-125 concentrator and retested before test results are reported. Specificity of positive results was studied by neutralization tests with human serum containing antibodies to HBAg.