Monoclonal Antibodies

Question 1

What are antibodies produced by?

Answer 1

B-lymphocytes - a type of white blood cell

Question 2

What are monoclonal antibodies produced from?

Answer 2

Lots of clones of a single white blood cell. This means all the antibodies are identical and will only target one specific protein antigen.

Question 3

Why can’t you just use the lymphocyte that made an antibody and grow more?

Answer 3

Lymphocytes don’t divide very easily.

Question 4

What can be done to get lots of identical cells?

Answer 4

Use tumour cells - they don’t produce antibodies but divide lots - so they can be grown really easily. You can fuse a mouse B-lymphocyte with a tumour cell to create a cell called a hybridoma. Hybridoma cells can be cloned to get lots of identical cells. These cells all produce the same antibodies (monoclonal antibodies). The antibodies can be collected and purified.

Question 5

What can you get monoclonal antibodies to bind to?

Answer 5

Anything you want, e.g. an antigen that’s only found on the surface of one type of cell. Monoclonal antibodies are really useful because they will only bind to this molecule - this means you can use them to target a specific cell or chemical in the body.

Question 6

How do pregnancy testing sticks detect the hormone HCG?

Answer 6

It is found in the urine of women only when they are pregnant.

Question 7

How are monoclonal antibodies used in pregnancy tests?

Answer 7

Pregnancy testing sticks.

1. The bit of the stick you week on has some antibodies to the hormone, with blue beads attached.
2. The test strip (the bit of the stick that turns blue if you’re pregnant) has some more antibodies to the hormone, with blue beads attached.
3. If you’re pregnant and you wee on the stick:
   - the hormone binds to the antibodies on the blue beads.
   - the urine moves up the stick, carrying the hormone and the beads.
   - the beads and hormone bind to the antibodies on the strip.
   - so the blue beads get stuck on the strip, turning it blue.
4. If you’re not pregnant and wee on the stick, the urine still moves up the stick, carrying the blue beads. But there’s nothing to stick the blue beads onto the test strip, so it doesn’t go blue.