HTL Immunohistochemistry & Special Stains

Question 1

What is the primary purpose of immunohistochemistry (IHC) in histotechnology?

Accepted Answer

To detect specific proteins and antigens in tissue

Answer

Immunohistochemistry (IHC) is a powerful technique that utilizes the specific binding of antibodies to antigens (proteins) within tissue sections. This allows histotechnologists and pathologists to precisely localize and identify specific cellular markers, pathogens, or disease-associated proteins. IHC is invaluable for diagnosis, prognosis, and therapeutic guidance, especially in oncology, by revealing the presence and distribution of target molecules.

Question 2

What is the primary advantage of using special stains in histology?

Accepted Answer

To selectively stain specific tissue components for better visualization

Answer

The primary advantage of using special stains in histology is their ability to selectively target and highlight particular cellular or extracellular components that are not adequately visualized by routine H&E staining. By selectively staining specific structures like collagen, elastic fibers, mucin, lipids, or microorganisms, these stains provide crucial diagnostic information that helps pathologists identify and characterize various diseases more precisely.

Question 3

What is the most commonly used marker in immunohistochemistry?

Accepted Answer

Antibodies that bind to specific antigens

Answer

Immunohistochemistry (IHC) relies on the highly specific binding of antibodies to target antigens within tissue samples. These antibodies are typically labeled (e.g., with enzymes or fluorochromes) to visualize the location and expression of the specific antigen, making them the fundamental marker for detection. They provide the specificity needed to identify particular cellular components.

Question 4

How does the biotin-avidin system function in immunohistochemistry?

Accepted Answer

It enhances signal detection by binding biotin-labeled antibodies

Answer

The biotin-avidin (or streptavidin) system is a common amplification strategy in immunohistochemistry. Biotin is conjugated to a secondary antibody, and avidin (or streptavidin) is then used, which has a very high affinity for biotin. This avidin is typically conjugated to an enzyme, allowing for multiple enzyme molecules to bind to each biotinylated antibody, thereby significantly enhancing the signal and improving detection sensitivity.

Question 5

What type of tissue components are best highlighted using periodic acid-Schiff (PAS) stain?

Accepted Answer

Carbohydrates and glycoproteins

Answer

The Periodic Acid-Schiff (PAS) stain is a histochemical technique specifically designed to detect carbohydrates and carbohydrate-rich macromolecules. Periodic acid oxidizes vicinal diols in carbohydrates to aldehydes, which then react with Schiff's reagent to produce a distinctive magenta color. This makes it ideal for highlighting structures like glycogen, mucins, and basement membranes in tissue sections.

(HTL) Histotechnology Certification Practice Test

(HTL) Histotechnology Certification Practice Test

HTL Immunohistochemistry & Special Stains