[Comparative study of technics of screening of carriers of HBs antigen].

The purpose of this study was to compare the results of 3 reverse passive haemagglutination techniques currently used by blood centers for the HBS antigen screening in donors' blood. A comparison was also made with 3 other techniques: Radio-immuno-assay (RIA), Counter-electrophoresis (CEP), Complement fixation (CF). The sera from 2.028 blood donors were screened by all those techniques, as well as 105 known sera, used as references (87 HBS antigen positive sera with different titers, 18 HBS antigen negative sera) and coming from 4 origins: NIH-Bethesda, Centre National de Transfusion Sanguine, Paris; Hôpital de la Pitié-Salpêtrière, Paris; Hôpital Broussais, Paris. The reverse passive haemagglutination techniques were shown to be slightly less sensitive than RIA and definitely more sensitive than CEP and CF, since 18 sera were HBS antigen positive with RIA (0.88%), 10 or 12 with haemagglutination (0.40-0.59%), 8 with CF (0.39%) and 7 with CEP (0.34%). The frequency of false positive results changed with the haemagglutination technique used (0.84% for WH.HBS, to 2.3% for Hepanosticon) and involved confirmatory tests (absorption and/or neutralisation). In sum, the sensitivity, specificity and practicability of the 3 haemagglutination techniques were shown to be nearly identical, with a slight but sure advantage for the WH.HBS in our experiment. Thus reverse passive haemagglutination techniques seem, at the present time, to be the best ones for HBS antigen screening when RIA cannot be applied.