Experimental validation of peptide immunohistochemistry controls

Area of Science:

• Biotechnology
• Clinical Diagnostics
• Quality Control

Background:

• Peptide immunohistochemistry (IHC) controls represent a novel format for verifying IHC assay performance.
• Formalin-fixed peptide epitopes on slides mimic native protein behavior in tissue sections.
• Existing quality control methods may not fully capture the complexities of IHC assays in diverse clinical settings.

Purpose of the Study:

• To evaluate the hypothesis that peptide IHC controls accurately reflect IHC staining performance in clinical laboratories.
• To assess the utility of peptide IHC controls as a practical quality assurance tool for clinical diagnostics.
• To determine the reproducibility and stability of the developed peptide IHC controls.

Main Methods:

• Development of an instrument for reproducible printing of peptide controls on microscope slides.
• Creation of software for automated measurement of stained control color intensity.
• A national study involving 109 clinical laboratories to correlate peptide control staining with HER-2 tissue staining.

Main Results:

• Automated printing of peptide spots demonstrated high reproducibility (4-8% CV).
• Peptide controls exhibited stability at <=4°C for at least 7 months.
• A strong correlation (r=0.87) was observed between peptide control staining and 3+ HER-2 tissue staining across laboratories.

Conclusions:

• Peptide IHC controls accurately reflect the analytical performance of IHC staining, including antigen retrieval.
• These controls are suitable for proficiency testing and verifying intralaboratory staining consistency using Levy-Jennings charts.
• Peptide IHC controls offer a standardized and high-throughput compatible solution for IHC quality assurance.