Monoclonal antibodies

Producing monoclonal antibodies

Monoclonal antibodies are identical antibodies, that have been produced from the same hybridoma cell. As a result of their ability to bind to only one protein antigen, they can be used to target chemicals and cells in the body and so have many different medical uses, e.g. in pregnancy testing.

How are they produced:

  1. Scientists obtain mice lymphocytes (a type of white blood cell that make antibodies but cannot divide), which have been stimulated to produce a specific antibody.

  2. They are combined with tumour cells (do not make antibodies but divide rapidly), to form a cell called a hybridoma cell.

  3. The hybridoma can divide to produce clones of itself, which all produce the same antibody.

  4. The antibodies are collected and purified.

Uses of monoclonal antibodies

1. Pregnancy tests. A hormone called human chorionic gonadotrophin (hCG) is present in the urine of women who are pregnant.

  1. There are two sections of the stick.

  2. The first section has mobile antibodies complementary to the hCG hormone- these antibodies are also attached to blue beads.

  3. The second section has stationary antibodies complementary to the hCG hormone which are stuck down to the stick.

  4. The individual urinates on the first section, and if hCG is present it binds to the mobile antibodies attached to blue beads to form hCG/antibody complexes.

  5. They are carried in the flow of liquid to the second section.

  6. The stationary antibodies then bind to the HCG/antibody complexes.

  7. As they are each bound to a blue bead, results in a blue line.

  8. This indicates that you are pregnant.

2. In laboratories to measure and monitor

  1. They can be used to measure and monitor levels of hormones or chemicals in the blood.

  2. The monoclonal antibodies are modified so that they will bind to the molecule you are looking for.

  3. The antibodies are also bound to a fluorescent dye.

  4. If the molecules are in the sample then the antibodies bind to it, and the dye can be observed.

  5. An example is screening donated blood for HIV infections.

3. In research to find or identify certain molecules on a cell or tissue

● The same method as above is applied, and scientists look for a build up of the fluorescence.

4. In the treatment of disease, e.g. cancer Cancer cells have antigens on their cell membranes known as tumour markers (not found on normal body cells), which can be targeted. There are three main ways to treat cancers using monoclonal antibodies.

a) Producing monoclonal antibodies that bind to the tumour markers in order to stimulate the immune system to attack the cell.

b) Using monoclonal antibodies to bind to receptor sites on the cell surface membrane of the cancer cells. This means growth-stimulating molecules cannot bind, stopping the cell from dividing.

c) Using monoclonal antibodies to transport toxic drugs, chemicals or radioactive substances as they can only bind to cancer cells.