Monoclonal Antibodies

• Monoclonal antibodies are identical copies of one type of antibody.
• Monoclonal Antibodies

  • Antibodies are proteins produced by a type of white blood called lymphocytes.
  • Pathogens have proteins on their surface called antigens.
  • When a pathogen infects the body, the lymphocytes recognise these antigens as foreign and attack them by producing antibodies.
• Monoclonal Antibodies

  • Antibodies bind to specific antigens on pathogens.
  • This means that only one type of antibody will bind to a matching antigen.
  • Scientists discovered that we could make antibodies to bind to antigens on other substances, and not just those on pathogens.
  • Once bound, the antigens - and the substances they are found on - are merged tightly together.
  • This makes them easier to identify and deal with.
• Monoclonal Antibodies

  1. Mouse lymphocytes (white blood cells) are stimulated with antigens to produce the desired antibody.
  2. The lymphocytes are removed from the mouse and combined with a tumour cell (myeloma) to make a cell called a hybridoma.
  3. The hybridoma cell can both divide and make the antibody.
  4. The hybridoma cells producing the desired antibody can be cloned to produce many identical cells that all produce this antibody.
  5. A large amount of the antibody can be collected and purified.
• Pregnancy Tests - Monoclonal Antibodies

  • Use monoclonal antibodies.
  • These have been designed to bind with a hormone called HCG which is found only in the urine of pregnant women.
  • Monoclonal antibodies are attached to the end of a pregnancy test stick onto which a woman urinates.
  • If she is pregnant, HCG will be present in her urine and will bind to the monoclonal antibodies on the test stick.
  • This will cause a change in colour or pattern which will indicate pregnancy.
  • These specific monoclonal antibodies in the pregnancy test will only bind with HCG.
• Cancer Diagnosis and Treatment with Monoclonal Antibodies

  • Cancerous cells have antigens.
  • Monoclonal antibodies can be designed to bind specifically with these antigens.
  • When injected into a person's body, the monoclonal antibodies will bind with these cancer cells and clump them together.
  • This makes it easier to identify a cancerous tumour, which can then be treated or removed.
• Cancer Diagnosis and Treatment with Monoclonal Antibodies

  Monoclonal antibodies have also been designed to treat cancer by:

  • Carrying drugs that have been attached to them to a tumour.
  • Encouraging your immune system to attack cancer cells directly.
• Other Diagnostic Uses of Monoclonal Antibodies

  • Monoclonal antibodies are also used in a similar way to identify and diagnose infections, such as HIV and AIDS, herpes and chlamydia.
  • Some monoclonal antibodies have been attached to dyes that will glow fluorescent under UV light.
  • This can make disease identification much easier.
• Benefits

  Monoclonal antibodies can be designed to bind to, and identify, almost any substance. They can be used for many purposes:

  • Testing for pregnancy by detecting HCG hormones in urine.
  • Testing for diseases such herpes and chlamydia, and HIV which can lead to the development of AIDS.
  • To treat conditions like cancer by carrying drugs directly to the tumour cells, and helping the immune system attack them.
  • Monoclonal antibodies can be produced quickly despite the fact that it can be time consuming when they are made for the first time.
• Limitations of Monoclonal Antibodies

  • The human body is very complicated.
  • Scientists originally thought that monoclonal antibodies would be a 'magic bullet' and would be able to identify and treat many medical conditions.
  • Tests have revealed, however, that this is not the case.
  • The interactions in the human body has resulted in unwanted side effects.
  • This means they are not as widely used by doctors as originally thought.
• Limitations of Monoclonal Antibodies

  • Monoclonal antibodies are also very expensive to produce.
• Ethical issues

  • An ethical issue is one in which people disagree for religious or other moral reasons.
  • The first step in making a monoclonal antibody is to inject a mouse with an antigen.
  • After it has produced antibodies, a small operation removes spleen cells, which then continue make the antibodies.
  • Some people disagree with this use of animals to produce monoclonal antibodies.
• Ethical Issues

  • In 2006 a drug trial involving humans using monoclonal antibodies to treat conditions such as arthritis and leukaemia.
  • Despite the individuals being given very low doses, it resulted in organ failure but was not fatal.
  • The monoclonal antibodies had been safely used in other animal trials before being used in human trials.
  • This is an example of how careful we must be during drug development.