monoclonal antibodies

• monoclonal antibodies are...


  identical antibodies
• what are antibodies produced by?

  B-lymphocytes
• what makes monoclonal antibodies identical and target one specific protein antigen?

  the fact that they're produced from lots of clones of a single B-lymphocyte
• hybridoma


  a cell hybrid produced in vitro by the fusion of a lymphocyte that produces antibodies and a myeloma tumour cell in order to produce a continuous supply of a specific antibody
• what can be obtained by cloning hybridoma cells?

  many identical cells that all produce the sae antibodies (monoclonal antibodies) that can then be collected and purified
• how are hybridoma cells made?

  1. inject a mouse with a specific antigen to stimulate an immune response

  2. collect B-lymphocytes (white blood cells that produce antibodies) from the mouse's spleen

  3. fuse the B-lymphocytes with myeloma cells (tumour cells that divide rapidly) to form hybridoma cells

  4. hybridoma cells are created, which can both produce antibodies and divide rapidly

  5. screen the hybridoma cells to find those producing the desired antibody

  6. clone the selected hybridoma cells to produce large amounts of identical monoclonal antibodies
• why are monoclonal antibodies useful?

  because they will only bind to a certain molecule which means you can use them to target a specific cell or chemical in the body
• how are monoclonal antibodies used in pregnancy tests?

  1. The woman urinates on the test stick, where the urine is absorbed and begins to travel along the test strip.

  2. The strip contains mobile monoclonal antibodies that are specific to hCG, the pregnancy hormone. These antibodies are attached to coloured dye particles.

  3. If hCG is present in the urine, it binds to these coloured antibodies, forming a hCG-antibody-dye complex.

  4. This complex moves along the strip with the flow of urine.

  5. The strip has a test line with a second set of immobilised monoclonal antibodies, also specific to hCG.

  • If hCG is present, the complex binds here and forms a visible coloured line, showing a positive pregnancy result.

  6. Further along the strip is a control line with a third set of immobilised antibodies that bind to any unbound coloured antibodies.

  • This produces a second line to show the test has worked properly, even if the result is negative.
• how can monoclonal antibodies by used to treat diseases?

  1. Cancer treatment - Monoclonal antibodies can be made to bind to cancer cell antigens:

  • This triggers the immune system to destroy the cancer cells.

  • Some antibodies block signals that cancer cells use to grow.

  • Others can carry toxic drugs or radioactive substances directly to the cancer cells without harming healthy cells.

  2. Infectious diseases - They can bind to pathogens or their toxins, neutralising them or making them easier for white blood cells to destroy.

  3. Other uses - For example, in autoimmune diseases, they can block immune responses that are attacking the body's own cells.
• how are monoclonal antibodies used n cancer treatment?

  1) Different cells in the body have different antigens on their cell surface. So you can make monoclonal antibodies that will bind to specific cells in the body (e.g. just liver cells).

  2) Cancer cells have antigens on their cell membranes that aren't found on normal body cells. They're called tumour markers.

  3) In the lab, you can make monoclonal antibodies that will bind to these tumour markers.

  4) An anti-cancer drug can be attached to these monoclonal antibodies. This might be a radioactive substance, a toxic drug or a chemical which stops cancer cells growing and dividing.

  5) The antibodies are given to the patient through a drip.

  6) The antibodies target specific cells (the cancer cells)

  because they only bind to the tumour markers.

  7) The drug kills the cancer cells but doesn't kill any normal body cells near the tumour.
• how can monoclonal antibodies by used to treat diseases?

  1. Locating or identifying specific molecules

  • Monoclonal antibodies can be made to bind to a specific molecule (antigen).

  • They're often tagged with a fluorescent dye or a radioactive marker, so scientists can see where the molecule is in a tissue or cell sample.

  
  

  2. Measuring levels of hormones or chemicals in the blood

  • For example, in pregnancy tests, monoclonal antibodies detect the hormone hCG in urine.

  • Similar tests can be used in research to measure specific proteins or hormones or testing blood samples for certain pathogens.

  
  

  3. Diagnosing diseases

  • In lab tests, monoclonal antibodies can detect infections or conditions like HIV or cancer by identifying specific markers.

  
  

  4. Scientific experiments

  • Researchers use them to study how the immune system works, to understand diseases, or to test how well new drugs bind to targets.
• pros of monoclonal antibodies

  - only bind to one specific antigen - very accurate.

  - can treat many diseases (e.g. cancer, infections).

  - can carry drugs straight to the diseased cells.

  - used in tests like pregnancy tests and disease diagnosis.

  - does not affect normal body cells in cancer treatment as opposed to standard chemotherapy and radiotherapy
• cons of monoclonal antibodies

  - expensive and slow to produce.

  - can cause side effects (e.g. allergic reactions, fever, vomiting, low blood pressure).

  - might not work for every patient.

  - involves using animals - some people find this unethical.