4.3.2.2 Uses of Monoclonal Antibodies

Question 1

What are the uses of monoclonal antibodies?

Answer 1

• for diagnosis e.g. in pregnancy tests
• in laboratories to measure and monitor chemicals in blood
• in research to locate or identify specific molecules in a cell or tissue
• to diagnose rumours
• to treat cancers

Question 2

What do pregnancy tests detect?

Answer 2

• The hormone called human chorionic gonadotrophin (hCG) is present in the urine of women who are pregnant - pregnancy test strips are designed to detect this hormone

Question 3

What are the different sections of pregnancy test stick used for?

Answer 3

• 2 sections of the stick
• 1st section has mobile antibodies complementary to the hCG hormone (these antibodies are also attached to blue beads
• 2nd section has stationary antibodies complementary to the hCG hormone which are stuck down on the stick

Question 4

How does a pregnancy test show someone is pregnant?

Answer 4

1. The individual urinates on the first section of the strip, and if hCG is present it binds to the mobile antibodies attached to blue beads to form hCG/antibody complexes
2. The urine moves up the stick, carrying the hormone attached to antibodies with the blue beads (carried in the flow of the liquid to second section)
3. The stationary antibodies bind to hCG antibody complexes (with blue beads and hormones)
4. As they are each bound to a blue beads, the beads get stuck on the strip turning it the colour blue (resulting in blue line)
5. This means the person is pregnant

Question 5

What happens on a pregnancy test if a woman isn’t pregnant?

Answer 5

if a woman isn’t pregnant the urine moves up the stick carrying the blue beads but there is no hCG attached to them to stick the blue beads on the test strip, so it does not turn blue

Question 6

What can monoclonal antibodies be used in labs to measure and monitor?

Answer 6

• can be used to measure and monitor levels of hormones or chemicals in the blood, or to detect pathogens

Question 7

How can monoclonal antibodies be used to measure and monitor chemicals in blood?

Answer 7

• the monoclonal antibodies are modified so that they will bind to a specific molecule
• the antibodies are also bound to a fluorescent dye
• if the molecules are in the sample then the antibodies bind to it, and the dye can be observed
• an example if screening donated blood for HIV infections

Question 8

How are monoclonal antibodies used to locate or identify specific molecules in a cell or tissue?

Answer 8

• by binding the monoclonal antibodies to a fluorescent dye
• scientists then look for a build up of the fluorescence

Question 9

How can monoclonal antibodies be used to diagnose tumours?

Answer 9

1. Radioactive substance is attached to the monoclonal antibody
2. The monoclonal antibody is then injected into the patient’s blood
3. The monoclonal antibody attaches itself to the antigen of the tumour cells
4. There is a concentration of radioactive monoclonal antibodies at the site of the tumour
5. Greater radiation is detected at the site of the tumour
6. This is detected and processed by a computer and an image of the tumour
7. This can be used to diagnose and treat the tumour

Question 10

How can monoclonal antibodies be used to treat cancers?

Answer 10

• the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing
• it delivers specific drugs to cancer cells meaning other health cells in the body remain unharmed and reduces the side-effects of the cancer treatment

Question 11

3 things that can be bound to monoclonal antibodies to help treat cancer:

Answer 11

• drugs
• radioactive material
• fluorescent materials

Question 12

Why aren’t monoclonal antibodies the ‘magic bullet’ some scientists thought they would be?

Answer 12

difficult to produce in large quantities

Question 13

Advantages of monoclonal antibodies:

Answer 13

• only bind to specific cells meaning healthy cells are not affected
• can be engineered to treat many different conditions
• we are now able to produce mouse-human hybrid cells to reduce the chance of triggering an immune response

Question 14

Disadvantages of monoclonal antibodies:

Answer 14

• difficult to attach monoclonal antibodies to drugs
• expensive to develop
• as they were produced from mice lymphocytes, they often triggered an immune response when used in humans
• difficult to produce in large quantities
• ethical issues must be considered
• create more side-effects than expected - not yet as widely used as everyone hoped when they were first developed