Detection of HBsAg in blood donors. A comparative study using radioimmunoassay, enzymeimmunoassay, reverse passive haemagglutination and latex tests.

Several "third generation" tests were compared: 5 reverse passive haemagglutination methods (RPHA), 2 enzyme immunoassays (EIA), 1 radioimmunoassay (RIA) and 1 latex test. As far as the sensitivity is concerned RPHA techniques are less sensitive than the RIA. However, differences exist among the different RPHA methods. RPHA methods which utilize human red cells demonstrated a better sensitivity than those which utilize animal red cells. The RIA is widely accepted for blood donor screening. The test is well standardized, highly sensitive and specific. Also the EIA has been found to be highly sensitive but showed a greater degree of non-specificity. Rapid HBsAg screening in blood donors can be performed by RPHA methods or by a latex test. For the latter Antigex TG was used. This test has a sensitivity which is similar to that of some the RPHA methods. The most striking results was the observation that Antigex TG can cause a prozone phenomenon. This phenomenon can be avoided when the serum specimen was spread out before the latex reagent was added.