A proper IHC tissue control should follow what parameters to insure optimal protocol performance?

• A. Show stable antigen expression between samples of the same tissue type
• B. Reflect changes in protocol performance by changes in staining intensity
• C. None of the above
• D. Show stable antigen expression and reflect changes in protocol performance

Answer: (D)

In IHC, a proper tissue control must serve two roles at once: it should show stable antigen expression across samples of the same tissue type so that differences you see are due to biology-free of technical noise, and it should reflect changes in protocol performance so you can detect when the staining run is drifting or failing. This dual requirement lets you trust that a strong, consistent control confirms the assay is working, while any change in its staining indicates a problem with the protocol, reagents, or processing. If the control doesn’t stay constant across similar tissues, you can’t attribute differences to the test samples; if it doesn’t respond to protocol changes, you won’t notice when the assay is off. Therefore, the best choice combines both stable expression and sensitivity to protocol performance, ensuring accurate, reliable results.