Question

Which of the following lab techniques is most commonly used to compare and quantify CD markers in cells?

• A. ELISA
• B. Western blot
• C. Flow cytometry
• D. IHC

Hint:

For CD marker analysis in cells, the answer is usually flow cytometry.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question focuses on the laboratory method used for "immunophenotyping," which involves identifying and counting cells based on their surface "Cluster of Differentiation" (CD) markers.
Step 2: Detailed Explanation:

Flow Cytometry: This is a laser-based technology used to analyze the physical and chemical characteristics of particles in a fluid as they pass through at least one laser.

Mechanism: Cells are labeled with fluorescently-tagged antibodies specific to CD markers (e.g., CD3 for T-cells, CD19 for B-cells). As the cells flow past the laser, they emit fluorescence, which the machine quantifies.

Quantification: Flow cytometry is unique because it can analyze thousands of cells per second and provide a quantitative percentage of cells expressing a specific marker (e.g., "30% of the cells are CD5 positive").

IHC vs. Flow: Immunohistochemistry (IHC) also identifies markers but on tissue slides. It is less "quantitative" for large numbers of individual cells compared to flow cytometry.

Western Blot: Used to detect a specific protein in a homogenized tissue sample, not to count individual whole cells.

Step 3: Final Answer:
Flow cytometry is the standard technique for the high-throughput quantification and comparison of CD markers on cell surfaces.