Effect of protease pretreatment on immunomorphologic demonstration of hepatitis-B-surface antigen in conventional paraffin-embedded liver biopsy material: quantitative evaluation.

The effect of protease pretreatment on the demonstration of hepatitis-B-surface antigen by immunofluorescence (IF) and the unlabeled peroxidase-antiperoxidase technique (PAP) in conventionally processed (formalin-fixed, paraffin-emmbedded) liver biopsy material was quantitatively assessed by microphotometry. Protease digestion significantly enhances the intensity of specific staining by both methods, and, in addition, suppresses non-specific background fluorescence. The sensitivity of the immunomorphologic test is significantly enhanced, and antigen in low amounts, for example hepatitis-B-surface antigen associated with liver cell membrane ('membrane' staining), is easily detected.