Monoclonal antibodies

Monoclonal antibodies (mAbs) are laboratory-produced molecules designed to serve as substitute antibodies that can restore, enhance, or mimic the immune system's attack on cells. They are a type of biological therapy used to treat various diseases, including some types of cancer, autoimmune diseases, and infectious diseases. Here's a detailed explanation:

Production

Monoclonal antibodies are created using a technique that involves:

1. Immunization: An animal, often a mouse, is immunized with an antigen that elicits an immune response.
2. Cell Fusion: B-cells (which produce antibodies) are harvested from the animal's spleen and fused with myeloma cells (a type of cancer cell that can grow indefinitely) to create hybridomas.
3. Selection: Hybridomas that produce the desired antibody are selected.
4. Cloning: These selected hybridomas are cloned to produce large quantities of identical (monoclonal) antibodies.

Mechanism of Action

Monoclonal antibodies work by specifically targeting antigens, which are unique molecules found on the surface of pathogens or abnormal cells. They can:

• Direct Targeting: Bind directly to antigens on pathogens or cancer cells, marking them for destruction by the immune system.
• Blocking: Block specific proteins or receptors on cells, interfering with cell signaling pathways essential for cell survival or proliferation.
• Immune Modulation: Engage other components of the immune system, such as T-cells or natural killer cells, to enhance the immune response.

Types of Monoclonal Antibodies

1. Murine: Derived from mouse proteins and can trigger an immune response in humans.
2. Chimeric: Part mouse and part human proteins, which reduce the likelihood of an immune response.
3. Humanized: Mostly human proteins with only small mouse protein segments.
4. Fully Human: Entirely human proteins, minimizing the risk of immune reactions.

Clinical Applications

1. Cancer Treatment: mAbs can target specific cancer cell antigens, such as HER2 in breast cancer (e.g., Trastuzumab) or CD20 in non-Hodgkin's lymphoma (e.g., Rituximab).
2. Autoimmune Diseases: They can block inflammatory pathways in diseases like rheumatoid arthritis (e.g., Infliximab).
3. Infectious Diseases: mAbs can neutralize pathogens, as seen with treatments for COVID-19 (e.g., Bamlanivimab).

Advantages

• Specificity: High specificity for their target antigens, leading to fewer off-target effects.
• Versatility: Can be engineered to carry drugs, toxins, or radioactive substances directly to diseased cells.

Limitations

• Cost: Production is complex and expensive.
• Immune Response: Potential for the human immune system to recognize them as foreign and mount an immune response, particularly with less humanized antibodies.
• Access: Limited access in low-resource settings due to high costs and logistical challenges.

Monoclonal antibodies represent a powerful tool in modern medicine, offering targeted treatment options with the potential for fewer side effects compared to traditional therapies.