Monoclonal Antibodies (Edexcel GCSE Biology)

Higher tier only

• Monoclonal antibodies are antibodies that are made by identical immune cells, these identical immune cells are clones of the parent cell
• Antibodies are Y shaped proteins made by lymphocytes, (see Human Defence Systems)
• The antibodies are specific to one binding site on one protein antigen and so are able to target a specific chemical or specific cells in the body
• They are produced by stimulating mouse lymphocytes to make a particular antibody by exposing them to an antigen

The antigen is injected into a mouse and the antibodies combined with a tumour cell to make clones of the antibody

• The lymphocytes are combined with a particular type of tumour cell to make a hybridoma cell
  • Tumour cells can divide repeatedly which is why they are used

• The hybridoma cell can both divide and produce the antibody
• Single hybridoma cells are cloned, resulting in many divisions, making high quantities of identical cells that all produce the same antibody
• A large amount of the antibody can be collected and purified ready for use

Higher tier only

• The cloned antibodies that are produced can be to a specific protein on the cell or a particular chemical
• Monoclonal antibodies have a variety of uses. Some examples include:
  • In pregnancy tests - monoclonal antibodies with blue beads attached bind to the HCG hormone (produced during pregnancy) to show a positive test
  • To diagnose certain diseases - in laboratories to measure the levels of hormones and other chemicals in blood (such as some cancer proteins), or to detect pathogens
  • To treat some diseases: for cancer the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. It delivers the substance to the cancer cells without harming other cells in the body
  • To locate blood clots - radioactively labelled monoclonal antibodies are used to bind to proteins in a blood clot. A special camera can then be used to make an image of the radiation and locate the potentially harmful blood clot

Use of monoclonal antibodies table

Higher tier only

• Monoclonal antibodies have the potential to make big improvements to diagnosis and treatment and when they were first developed there were hopes for their use to become widespread
• However monoclonal antibodies create more side effects than expected which has hampered their use

Monoclonal antibodies table