Immunotherapy: Monoclonal Antibodies: Videos & Practice Problems

Monoclonal antibodies (MABs) are identical antibodies from a single B lymphocyte clone, targeting a specific antigen epitope with high affinity. To overcome the limited in vitro lifespan of B cells and plasma cells, hybridoma technology fuses antibody-producing B cells with immortal myeloma cells, enabling continuous proliferation and large-scale monoclonal antibody production. This method supports research and immunotherapy for diseases like cancer and autoimmune disorders. The process involves antigen immunization, B cell isolation, fusion with myelomas, selective culturing, and screening for desired antibody specificity, enhancing adaptive immunity and therapeutic antibody availability.

Immunotherapy: Monoclonal Antibodies

Monoclonal antibodies, often abbreviated as MABs, are identical antibodies produced by clones derived from a single B cell. The term "monoclonal" reflects their origin from a single clone, emphasizing their uniformity. These antibodies exhibit high specificity by binding to the same single epitope on an antigen, meaning they target the exact same spot. This precise binding ability makes monoclonal antibodies particularly useful for blocking or neutralizing specific antigen sites, which is valuable in treating various diseases such as cancer, autoimmune disorders, and infections.

Monoclonal antibodies are generated when a single B cell proliferates through mitosis, creating a clone of identical B cells. These B cells can then differentiate into plasma cells that produce the monoclonal antibodies. However, a significant challenge arises because B cells and plasma cells are relatively short-lived in vitro, or outside the body in laboratory conditions. This limited lifespan restricts the quantity of monoclonal antibodies that can be harvested, often resulting in insufficient amounts for research and therapeutic applications.

To overcome this limitation, it is essential to develop methods that enable the large-scale production of monoclonal antibodies. Such techniques ensure a sustainable supply for both scientific study and clinical treatment, addressing the scalability problem inherent in relying solely on B cells and plasma cells. Understanding the biology of monoclonal antibodies and their production is crucial for advancing immunotherapy and improving disease management strategies.

Large-Scale Production on Monoclonal Antibodies

Monoclonal antibodies are produced on a large scale by creating hybridoma cells, which combine the antibody-producing ability of B cells with the continuous proliferation capacity of myeloma cells. B cells and plasma cells alone are short-lived in vitro, limiting the quantity of monoclonal antibodies that can be harvested. To overcome this, B cells are fused with myeloma cells—cancerous plasma cells that proliferate indefinitely but do not produce antibodies. This fusion results in hybridoma cells that can both multiply continuously and produce specific monoclonal antibodies against a target antigen.

The process begins by injecting a mouse with the antigen of interest to stimulate its immune system. After the immune response develops, B cells are isolated from the mouse’s spleen; many of these B cells will produce antibodies targeting the antigen, though not all. Simultaneously, myeloma cells are cultured. The B cells and myeloma cells are then chemically fused in vitro to form hybridomas. These hybridoma cells are cultured on selective media that supports only their growth, eliminating unfused cells. Since not all hybridomas produce the desired antibody, screening is essential to identify and select the single hybridoma clone that produces the monoclonal antibody specific to the antigen.

Once identified, this hybridoma clone can be cultured indefinitely, enabling the production of large quantities of monoclonal antibodies for research and therapeutic use. This method ensures a consistent and renewable source of antibodies with high specificity, which is crucial for applications such as diagnostic tests, targeted therapies, and biomedical research.

Immunotherapy: Monoclonal Antibodies Example 1

Monoclonal antibodies are highly specific proteins produced by B cells that recognize a particular antigen. For these antibodies to effectively recognize the antigen of interest, the immune system must first be exposed to that antigen. This exposure occurs when the antigen is injected into a mouse, allowing the mouse's immune system to respond and generate B cells that produce antibodies specific to the antigen. Importantly, B cell maturation is an antigen-independent process, meaning that B cells develop their initial antibody specificity without prior antigen exposure. The antigen encounter happens after maturation, stimulating the production of antibodies tailored to the antigen.

In the process of creating monoclonal antibodies, cancerous myeloma cells are used as fusion partners with B cells to form hybridomas, which can be cultured indefinitely to produce large quantities of the desired antibody. However, these myeloma cells are not injected with the antigen; instead, the antigen is introduced into the mouse to activate the immune response. Additionally, the shape and specificity of antibodies are not artificially designed in the laboratory but are naturally determined by the B cells' biological processes.

Thus, the critical step for monoclonal antibody production is the injection of the antigen into the mouse, enabling the immune system to generate B cells that produce antibodies specific to that antigen. This understanding highlights the natural biological mechanisms underlying antibody specificity and the role of antigen exposure in adaptive immunity.

Why are the mouse B cells that are responsible for producing monoclonal antibodies hybridized with cancerous myeloma cells?

• A. B cells cannot replicate forever but cancerous myeloma cells can.
• B. B cells and myeloma cells create antibodies, hybridizing them increases the number of antibodies produced.
• C. Hybridization will ensure that the antibodies created by the B cells will recognize and bind to the myeloma cells.
• D. Hybridization will ensure that the antibodies have human qualities and will not be rejected by the patient’s body.

Answer: (A)

Which of the following is not a characteristic of monoclonal antibodies?

• A. Monoclonal antibodies are produced by hybridoma clones.
• B. Monoclonal antibodies are natural antibodies created by the immune system to fight disease.
• C. All monoclonal antibodies in a single batch are identical and therefore recognize the same epitope.
• D. Monoclonal antibodies can be used for various diagnostic and treatment therapies for disease.

Answer: (B)

Here’s what students ask on this topic:

What are monoclonal antibodies and how are they produced?

Monoclonal antibodies (MABs) are identical antibodies produced by clones derived from a single B lymphocyte. They specifically recognize and bind to the same epitope on an antigen, making them highly specific. To produce monoclonal antibodies, B cells are first stimulated by an antigen. However, B cells and plasma cells have a short lifespan in vitro, limiting antibody production. To overcome this, B cells are fused with long-lived myeloma cells, which are cancerous plasma cells that proliferate indefinitely but do not produce antibodies. This fusion creates hybridoma cells that combine the ability to produce specific antibodies with continuous growth. These hybridomas can be cultured to produce large quantities of monoclonal antibodies for research and therapeutic use.

Why is hybridoma technology important for large-scale monoclonal antibody production?

Hybridoma technology is crucial because B cells and plasma cells alone have a limited lifespan in vitro, producing insufficient monoclonal antibodies for research and treatment. By fusing B cells with myeloma cells, hybridoma cells are created that can both continuously proliferate and produce specific monoclonal antibodies. This allows for the large-scale production of antibodies targeting a particular antigen. The process involves immunizing a mouse with an antigen, isolating B cells, fusing them with myeloma cells, and selecting hybridomas that produce the desired antibody. This technology enables consistent, scalable antibody production essential for immunotherapy and scientific research.

How does the process of selecting hybridoma cells work in monoclonal antibody production?

After fusing B cells with myeloma cells to form hybridomas, the cells are cultured on selective media that only allows hybridomas to survive. Since not all hybridomas produce the desired antibody, a screening process is necessary. Scientists test the antibodies produced by each hybridoma to identify those that specifically bind to the antigen of interest. Once a hybridoma producing the correct monoclonal antibody is identified, it is cloned and cultured indefinitely. This ensures a continuous and pure supply of the specific monoclonal antibody needed for research or treatment.

What diseases can monoclonal antibodies be used to treat?

Monoclonal antibodies are used to treat a variety of diseases due to their high specificity for antigens. They are commonly applied in cancer therapy to target tumor cells, autoimmune disorders to modulate immune responses, and infectious diseases to neutralize pathogens. Their ability to bind precisely to specific epitopes allows them to block or mark harmful cells or molecules for destruction. This targeted approach reduces side effects compared to traditional treatments and enhances the effectiveness of immunotherapy.

What role do myeloma cells play in monoclonal antibody production?

Myeloma cells are cancerous plasma cells that can proliferate indefinitely in vitro but do not produce antibodies on their own. In monoclonal antibody production, myeloma cells are fused with antibody-producing B cells to create hybridoma cells. These hybridomas inherit the ability to produce specific antibodies from the B cells and the continuous growth capability from the myeloma cells. This fusion overcomes the short lifespan of B cells in culture, enabling large-scale, sustained production of monoclonal antibodies for research and therapeutic use.