Question

What is the purpose of using HAT medium in hybridoma technology?

• A. To kill unfused B-lymphocytes
• B. To kill unfused myeloma cells
• C. To selectively allow growth of only hybridoma cells
• D. To increase the rate of cell fusion

Hint:

Remember the sequence of Hybridoma Technology: \[ \boxed{\text{B-Lymphocyte} + \text{Myeloma Cell} \longrightarrow \text{Hybridoma} \longrightarrow \text{HAT Selection} \longrightarrow \text{Monoclonal Antibody Production}} \] HAT medium does not increase cell fusion; it only selects successfully fused hybridoma cells by eliminating unfused myeloma cells and allowing hybridomas to survive.

Answer 1

The Correct Option is C

Concept: Hybridoma technology is a technique used for the production of monoclonal antibodies. It involves the fusion of antibody-producing B-lymphocytes with immortal myeloma cells. After fusion, the cells are cultured in a special selective medium called HAT medium (Hypoxanthine-Aminopterin-Thymidine medium), which allows only hybridoma cells to survive.
• Hybridoma technology was developed by Georges Köhler and César Milstein.
• B-lymphocytes produce specific antibodies but have a short lifespan.
• Myeloma cells divide indefinitely but do not produce antibodies.
• Fusion of these two cells produces hybridoma cells, which are both immortal and antibody-producing.
• HAT medium is used to select only the successfully fused hybridoma cells.

Step 1: Understand the composition of HAT medium.
HAT medium contains:
• Hypoxanthine
• Aminopterin
• Thymidine Aminopterin blocks the de novo pathway of DNA synthesis. Therefore, cells must use the salvage pathway to synthesize DNA. \[ \boxed{\text{HAT} = \text{Hypoxanthine} + \text{Aminopterin} + \text{Thymidine}} \]

Step 2: Explain how HAT medium selects hybridoma cells.
After cell fusion, three types of cells are present:
• Unfused B-lymphocytes
• Unfused myeloma cells
• Hybridoma cells
• Unfused B-lymphocytes possess the salvage pathway but have a limited lifespan, so they die naturally after a few days.
• Unfused myeloma cells lack the enzyme HGPRT required for the salvage pathway. Since aminopterin blocks the de novo pathway, these cells cannot synthesize DNA and die in HAT medium.
• Hybridoma cells inherit immortality from myeloma cells and the salvage pathway enzyme from B-lymphocytes. Therefore, they survive and multiply.

Step 3: Choose the correct option.
The primary purpose of HAT medium is to eliminate unfused cells and allow only hybridoma cells to survive and proliferate. \[ \boxed{Option (C) is the correct answer. \]