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University revision · Cellular Pathology

Immunohistochemistry

Question 1 of 100 Course: Biomedical Science(Degree)
Q1
Which of these factors can lead to false-negative IHC results?
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About this topic

Immunohistochemistry (IHC) is a cornerstone technique in modern diagnostic pathology, enabling the visualization of specific antigens in tissue sections using antibody-based detection. This tertiary-level topic delves into the fundamental principles of antigen-antibody interactions, the production and use of monoclonal and polyclonal antibodies, and the various labeling systems including enzyme labels like horseradish peroxidase and alkaline phosphatase. It covers the complete IHC procedure from tissue fixation and antigen retrieval to blocking, primary antibody application, detection methods (direct, indirect, PAP, ABC, polymer-based), and counterstaining. For Zambian college and university students in biomedical science, histopathology, or medical laboratory science programs, mastering IHC is crucial for tumor classification, infectious agent identification, prognostic factor assessment, and research applications. This knowledge directly supports exam preparation, practical laboratory competency, and future careers in hospitals, research institutes, and diagnostic centers throughout Zambia's healthcare system.

What you'll practise (50 questions)

  1. What is the primary purpose of antigen retrieval in immunohistochemistry?
  2. What is the term for the laboratory technique that uses antibodies to detect specific antigens in tissue sections?
  3. Immunohistochemistry uses antibodies to detect specific antigens in tissue sections. True or false?
  4. Which of the following is a common method for detecting protein expression in tissues?
  5. Which technique is used to detect specific proteins in a tissue sample using antibodies?
  6. Immunohistochemistry (IHC) is a technique that uses radiolabeled antibodies to locate specific antigens in tissue sections.
  7. True or False: Immunohistochemistry is used to detect specific proteins in tissue sections.
  8. What is the primary purpose of immunohistochemistry (IHC)?
  9. Which of the following is a clinical application of IHC?
  10. In IHC, monoclonal antibodies are derived from identical immune cells and bind to a single epitope.
  11. Which enzyme is most commonly used as a label in IHC?
  12. What is the purpose of antigen retrieval in IHC?
  13. Which chromogen produces a brown insoluble precipitate when used with peroxidase in IHC?
  14. The indirect IHC method uses a labeled secondary antibody to detect the primary antibody.
  15. Which of the following is an advantage of the biotin-streptavidin method in IHC?
  16. Immunofluorescence uses antibodies conjugated to fluorescent labels to detect antigens in tissues.
  17. Which factor can lead to false-positive staining in IHC?
  18. What is the role of a counterstain in IHC?
  19. The PAP (peroxidase-antiperoxidase) method is more sensitive than the indirect conjugate method.
  20. Which component of the IHC procedure is primarily responsible for creating the visible colored precipitate at the antigen site?
  21. Heat-Induced Epitope Retrieval (HIER) involves heating tissue sections to approximately 100°C.
  22. What is the main difference between monoclonal and polyclonal antibodies in terms of specificity?
  23. Blocking with normal serum is performed in IHC to prevent non-specific binding of antibodies.
  24. Which staining technique uses an unlabeled primary antibody, a biotinylated secondary antibody, and a preformed avidin-biotin-peroxidase complex?
  25. What is a primary disadvantage of the direct IHC method compared to indirect methods?
  26. The polymer-based detection system in IHC uses a dextran backbone to carry multiple enzyme and secondary antibody molecules.
  27. What is the primary function of the 'linking antibody' in the PAP (Peroxidase-Anti-Peroxidase) method?
  28. Why is it necessary to quench endogenous peroxidase activity before proceeding with an HRP-based IHC stain?
  29. The APAAP (Alkaline Phosphatase-Anti-Alkaline Phosphatase) method is particularly useful for staining tissues with high endogenous peroxidase.
  30. In immunofluorescence, what does the term 'emission maximum' refer to?
  31. Which step in tissue processing for IHC is critical for removing paraffin and rehydrating the tissue?
  32. A false-negative IHC result can be caused by over-fixation of the tissue in formalin.
  33. What does the chromogen 3-Amino-9-Ethylcarbazole (AEC) produce, and what is a key handling consideration?
  34. The principle of the 'enzyme bridge' method in IHC most closely resembles which subsequent technique?
  35. In a diagnostic IHC report, a tumor showing '3+' membrane staining for HER2 is considered positive for overexpression.
  36. Which of the following best describes the role of a chromogen in IHC?
  37. The 'Tyramine Signal Amplification' (TSA) method increases sensitivity by depositing numerous biotin molecules at the antigen site.
  38. For which primary application is the direct IHC method still commonly used today?
  39. What is a major consequence of under-digestion during Protease-Induced Epitope Retrieval (PIER)?
  40. The use of 'charged' or 'positively coated' slides in IHC is primarily to improve tissue adhesion during harsh retrieval steps.
  41. In the context of IHC quality control, what is the purpose of running a 'negative control' slide?
  42. Which component of an antibody is responsible for its specific binding to an antigen?
  43. Cryostat sections are typically used for immunofluorescence staining of renal biopsies because they preserve antigenicity better than formalin-fixed paraffin-embedded (FFPE) sections for certain targets.
  44. What is the primary reason for including a 'positive tissue control' in every IHC run?
  45. In the biotin-streptavidin detection system, what property of streptavidin makes it superior to avidin for reducing background staining?
  46. What is the consequence of using an antibody at a concentration that is too high in an IHC assay?
  47. The indirect immunofluorescence method involves a fluorochrome-labeled secondary antibody.
  48. What is the defining characteristic of a 'polymeric' detection system in IHC?
  49. Which of the following best describes the purpose of the 'post-primary' step in some advanced polymer systems?
  50. A 'checkerboard titration' is performed to optimize both primary antibody and antigen retrieval conditions simultaneously.

Answer each question above to see the correct answer and a full explanation.