2.6.5 Monoclonal Antibodies

What Are Monoclonal Antibodies?

1. Definition:

• Antibodies produced by a single clone of plasma cells that are specific to one antigen.

2. Production:

• Monoclonal antibodies are created by fusing a B cell that produces a specific antibody with a myeloma cell (a type of cancer cell) to form a hybridoma.
• Hybridomas divide indefinitely and produce large quantities of the specific antibody.

Uses of Monoclonal Antibodies:

1. Direct Therapy:

• Monoclonal antibodies target specific antigens on cancer cells to destroy them as part of an immune response.
• Example:
• Herceptin binds to antigens on breast cancer cells, helping the immune system destroy these cells.

2. Indirect Therapy:

• Monoclonal antibodies are used to deliver drugs like cytotoxic agents or radioactive substances directly to cancer cells.
• The antibody ensures that the treatment targets only the cells with the specific antigen, reducing damage to healthy cells.

3. Diagnosis:

• Monoclonal antibodies are used to detect specific antigens in the body, helping diagnose diseases.

• Example:
• Detecting prostate-specific antigen (PSA) in blood tests for prostate cancer.

4. Pregnancy Testing:

• Monoclonal antibodies in home pregnancy kits bind to the hormone human chorionic gonadotrophin (hCG) found in urine during pregnancy.
• A colour change on the test strip confirms the presence of hCG.

5. Laboratory Research:

• Used to locate and isolate specific molecules or study interactions between antigens and antibodies.

Advantages of Monoclonal Antibodies:

• Specificity: Highly specific to the target antigen, reducing side effects.
• Versatility: Can be used for diagnosis, therapy, and research.
• Targeted Treatment: Deliver treatments directly to diseased cells, sparing healthy tissues.

Limitations and Ethical Considerations:

1. Side Effects:

• Monoclonal antibody therapies can cause immune reactions, such as fever, nausea, or low blood pressure.

2. Production Challenges:

• Producing monoclonal antibodies is expensive and time-consuming.

3. Ethical Issues:

• The production process often involves the use of mice to generate hybridomas, raising ethical concerns about animal testing.

Examples of Monoclonal Antibodies in Use:

1. Herceptin:

• Targets HER2 receptors on breast cancer cells, aiding their destruction.

2. Rituximab:

• Used in treating non-Hodgkin lymphoma by targeting B cells.