Comparison of different double immunostaining protocols for paraffin embedded liver tissue

Area of Science:

• Histopathology
• Immunohistochemistry
• Pathology

Background:

• Double immunostaining protocols are often limited to fresh frozen tissues or require antibodies from different species.
• Liver tissue presents unique challenges for immunostaining, including necrosis and high protein content.
• Archived, paraffin-embedded liver tissue requires specific, reliable double immunostaining methods.

Purpose of the Study:

• To evaluate and compare different double immunostaining protocols for archived, paraffin-embedded liver tissue.
• To identify a reliable protocol with high sensitivity, specificity, and low background staining.
• To assess protocols using same-species primary antibodies for pathological liver specimens.

Main Methods:

• Comparison of peroxidase-anti-peroxidase (PAP/APAP), labelled-avidin-biotin (LAB/LAB), and digoxigenin-anti-digoxigenin (dig-a-dig/PAP) techniques.
• Utilized cytokeratin antibodies and a PCNA antibody for antigen detection.
• Evaluated protocols based on sensitivity, specificity, and non-specific background staining.

Main Results:

• All compared techniques demonstrated high sensitivity and specificity.
• PAP/APAP technique resulted in higher background staining compared to LAB/LAB and dig-a-dig/PAP.
• LAB/LAB protocol offered a superior time/cost relationship compared to dig-a-dig/PAP.

Conclusions:

• A modified LAB/LAB protocol is recommended for simultaneous antigen detection in archived liver tissue.
• The LAB/LAB protocol provides a reliable, sensitive, and specific method with manageable background staining.
• This protocol addresses the challenges of immunostaining in difficult pathological liver specimens.