Monoclonal antibodies - Higher - OCR GatewayUses of monoclonal antibodies - Higher

Pregnancy test kits

Pregnancy test kits use monoclonal antibodies. These have been designed to bind with a hormone called hCG which is only found 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

Cancerous cells have antigens on their surface. Monoclonal antibodies can be designed to bind specifically with these antigens. As one monoclonal antibody will only recognise one specific antigen, different monoclonal antibodies have to be developed to recognise different forms of cancer. When injected into a person's bloodstream, the monoclonal antibodies travel around the body. They then bind to the antigens on the cancer cells. The antibodies may also carry markers that make it easy for doctors to see where they build up in the body. The marker may be a dye that will glow fluorescent under UV light. This makes it easier for doctors to identify a cancerous tumour, which can then be treated or removed. Monoclonal antibodies have been used successfully to detect and treat prostate cancer in men.

Cancer treatment

Monoclonal antibodies have also been designed to treat cancer by:

• Targeting drugs that have been attached to the monoclonal antibody directly to the tumour. The drugs could be radioactive or toxic substances. The advantages compared to using radiotherapy or chemotherapy are that only the cancer cells are targeted, leaving the healthy cells unaffected. This reduces side effects.
• Encouraging the white blood cells in your immune system to attack the cancer cells directly.

Other diagnostic uses

Monoclonal antibodies are also used in a similar way to identify and diagnose infections, such as HIV, herpes and chlamydia.