Uses of Monoclonal Antibodies (AQA GCSE Biology): Revision Note

Uses of monoclonal antibodies

Higher Tier Only

• Monoclonal antibodies are specific to one antigen (a particular protein) or a particular chemical: the shape of the antibody is complementary to the shape of that antigen, so it binds to that antigen and nothing else

Pregnancy tests

• Monoclonal antibodies specific to a hormone produced in pregnancy, human chorionic gonadotropin (HCG) will bind to the hormone if present and produce a colour change

• Test strips also have a control area where free monoclonal antibodies bind. A colour change in the control area shows the test has worked, so a result can only be read if the control area has changed colour

Diagnosis of disease

• The monoclonal antibodies are specific to antigens found on the surface of pathogens, blood clots or cancer cells

• They also contain markers that help the doctors to find the location of them. It is used in the test for prostate cancer

Measuring and monitoring

• They can be used to detect not only the presence of a chemical or pathogen but the quantity

• For example drug testing of athletes and screening blood for the presence of HIV

Research

• Monoclonal antibodies with a fluorescent dye attached can be used by scientists to detect specific molecules in a cell or tissue

Treating disease

• Many types of cancer are difficult to treat. Monoclonal antibodies can be used in three ways to treat cancer:

1. Use of the monoclonal antibodies to trigger immune cells to destroy them

2. Using monoclonal antibodies to block receptors, which stops them growing and dividing

3. Carry a toxic drug, a radioactive substance or a chemical that stops cells growing and dividing to the cancer cells. The antibody binds only to antigens on the cancer cells, so the attached substance kills the cancer cells or stops them growing and dividing, without harming other body cells

Advantages & disadvantages of monoclonal antibodies

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

Advantages

• They only bind to specific molecules on diseased or damaged cell – they do not affect healthy cells

• Highly specific so can be produced to treat a range of conditions

• Hoped to be a cheaper procedure, and a tried and tested method of treating conditions

Disadvantages

• Caused more side effects than first expected. Antibodies made using mouse lymphocytes may be rejected by the human body. Antibodies made using human lymphocytes are less likely to be rejected

• It is an expensive process at the moment

• Producing specific monoclonal antibodies is proving to be more difficult than expected