Detection of hepatitis-B surface antigen in plasma samples by reversed passive haemagglutination tests

A comparison of two commercial reversed passive haemmagglutination tests with a counter-immunoelectrophoretic test, used to detect hepatitis-B surface antigen in reconstituted freeze-dried plasma, showed an increase in the number of positive results by the haemagglutination tests. No difficulty was encountered with the appearance of non-specific agglutination provided the plasma was heated at 60 degrees C for 30 min, frozen overnight at -35 degrees C, thawed and centrifuged before testing.