Assessing the potential of immunohistochemistry for systematic gene expression profiling

Area of Science:

• Immunology
• Molecular Biology
• Biotechnology

Background:

• Immunohistochemistry (IHC) is a key technique for visualizing protein expression at cellular and subcellular levels.
• Its application for genome-wide expression screening requires robust validation of antibody performance.

Purpose of the Study:

• To assess the success rate and specificity of monoclonal antibodies for genome-wide IHC screening.
• To evaluate antibody performance on both frozen and formalin-fixed paraffin-embedded (FFPE) tissues.

Main Methods:

• A panel of 35 monoclonal antibodies targeting 5 CD antigens was pre-screened on frozen tissue sections.
• Antibodies were further tested on FFPE tissue sections and human tissue microarrays (frozen and FFPE).
• Staining success, specificity, and potential cross-reactivity were systematically evaluated.

Main Results:

• 19 out of 35 antibodies showed successful staining on frozen sections, with varying success rates per antigen.
• 16 of these antibodies also stained FFPE tissues, indicating broad applicability.
• Tissue microarrays revealed consistent staining patterns for some antibodies, but also highlighted issues like cross-reactivity and fixation-dependent changes in staining intensity and quality.

Conclusions:

• Immunohistochemistry has potential for describing protein expression of unknown genes.
• Systematic evaluation of antibody specificity and sensitivity is essential for reliable genome-wide expression profiling using IHC.
• Fixation methods significantly impact antibody staining, necessitating careful consideration for accurate interpretation.