Comparison of the reversed passive hemagglutination with radioimmunoassay methods for hepatitis B antigen

Radioimmunoassay for the detection of hepatitis B antigen has been accepted in many diagnostic laboratories now. The question of nonspecific positives has always been a matter of controversy. Two improved radioimmunoassay tests, namely Ausria II-125 by Abbott Laboratories and a radioimmunoassay method by Connaught Laboratories Limited (Hebria), were compared with the original Ausria 125I. Included in the comparison was the reversed passive hemagglutination test (Auscell, Abbott). Five hundred sera of clinical patients were tested. Fifty-five or 11% were found to have hepatitis B antigen. Three tests, Ausria 125I, Ausria II-125, and Hebria showed the same number of positive sera, whereas Auscell missed one. However, Ausria 125I indicated two additional false positives. Dilution experiments, however, indicated that Ausria II-125 and Hebria were the most sensitive tests, with the reversed passive hemaglutination showing the least sensitivity. Therefore, the new Ausria II-125 and the Hebria radioimmunoassay tests are preferable in view of their sensitivity and specificity.