Monoclonal antibodies and their uses

In a nutshell

Scientists have engineered antibodies known as monoclonal for lots of different uses such as pregnancy tests, treating cancer, detecting chemical or hormone levels in the blood, testing blood samples for pathogens and locating specific molecules on cells or tissue.

Monoclonal antibodies

Definition

Monoclonal antibodies are identical antibodies made by identical immune cells.

Antibodies are produced by a type of white blood cell called B-lymphocytes. Monoclonal antibodies are produced from lots of clones of a single B-lymphocyte, this means they are all identical and will only target one specific protein antigen.

However, these lymphocytes do not divide very easily. Tumour cells don't produce antibodies but they do divide very easily. Therefore, scientists fuse a mouse B-lymphocyte with a tumour cell to create a cell called a hybridoma. Hybridoma cells can be cloned to produce lots of identical cells that will all produce monoclonal antibodies. These antibodies can then be collected and purified.

Biology; Health, disease and the development of medicines; KS4 Year 10; Monoclonal antibodies and their uses - Higher — A mouse is injected with a chosen antigen (1), Fast-dividing tumour cells from the lab (2), B-lymphocytes taken from the mouse (3), B-lymphocyte fused with a tumour cell (4), Hybridoma (5), Hybridoma divides quickly to produce many clones that produce monoclonal antibodies.

Scientists can make monoclonal antibodies that bind to any antigen. This is useful because the antibody will be specific to the target meaning it will only bind to the target.

Pregnancy tests

Monoclonal antibodies are used in pregnancy tests. A hormone called HCG is found in urine during the early stages of pregnancy. Pregnancy test sticks detect this hormone.

Biology; Health, disease and the development of medicines; KS4 Year 10; Monoclonal antibodies and their uses - Higher — A. a pregnancy test, B. a positive pregnancy test, C. a negative pregnancy test

1.	The part of the stick you urinate on.
2.	Antibodies specific to HCG with blue beads attached.
3.	The test strip (the part that turns blue if you're pregnant) .
4.	Antibodies are stuck down. The test strip has more antibodies specific to HCG stuck onto it.
5.	Hormone (HCG) bound to antibody that is attached to a bead.
6.	The beads are carried in a flow of liquid towards the test strip.
7.	If you're pregnant, the hormone binds to the antibodies with the blue beads attached and the urine moves up the stick carrying the hormone and the beads. The beads and hormones bind to the antibodies on the test strip. The blue beads get stuck on the strip turning it blue.
8.	If you're not pregnant, the urine still moves the blue beads to the test strip, but as there is no hormone, nothing sticks to the test strip so it doesn't go blue.

Treating diseases with monoclonal antibodies

Different cells in the body have different antigens on their surface, this means you can make monoclonal antibodies that will bind to specific cells in the body. Cancer cells have antigens on their cell membranes that are not found on normal body cells, they're called tumour markers. Monoclonal antibodies that bind to tumour markers can be used to treat cancer.

An anti-cancer drug can be attached to these monoclonal antibodies. This could be a radioactive substance, a toxic drug or a chemical that stops the cancer cells from growing and dividing. The antibodies are given to a patient through a drip, they only target the specific cancer cells because they only bind to tumour markers. This means that the drugs kill the cancer cells but not any normal body cells near the tumour.

Biology; Health, disease and the development of medicines; KS4 Year 10; Monoclonal antibodies and their uses - Higher

1.	A monoclonal antibody
2.	An anti-cancer drug
3.	The drug attached to an antibody
4.	The antibody binds to tumour markers on the cancer cell
5.	Tumour markers
6.	Body cells
7.	Cancer cells

Other uses of monoclonal antibodies

1.	Bind to hormones and other chemicals in the blood to measure their levels.
2.	Test blood samples in laboratories for certain pathogens.
3.	Locate specific molecules on a cell or in a tissue.

Locating specific molecules on a cell or in a tissue

1.	Firstly, monoclonal antibodies are made that will bind to the specific molecules you are looking at.
2.	The antibodies are bound to a fluorescent dye.
3.	If the molecules are present in the sample, the monoclonal antibodies will attach to them and then can be detected using the dye.

Problems with monoclonal antibodies

Although monoclonal antibodies have a lot fewer symptoms than traditional cancer treatments like chemotherapy and radiotherapy, they cause more side effects than originally expected. These include fever, vomiting and low blood pressure. Therefore, they are not as widely used as scientists originally expected.