Monoclonal Antibodies¶
Part of 4.3 Infection and Response.
Monoclonal antibodies are useful because one cloned cell line makes one type of antibody, so every molecule binds to the same target. This makes them powerful tools for testing, imaging and treatment.
Learning Objectives¶
| ID | Official specification wording | Main teaching sections |
|---|---|---|
4.3.2-lo-1 |
4.3.2.1 Students should be able to describe how monoclonal antibodies are produced. 4.3.2.1 Monoclonal antibodies are produced from a single clone of cells. The antibodies are specific to one binding site on one protein antigen and are able to target a specific chemical or specific cells in the body. 4.3.2.1 They are produced by stimulating mouse lymphocytes to make a particular antibody. The lymphocytes are combined with a particular kind of tumour cell to make a cell called a hybridoma cell. The hybridoma cell can both divide and make the antibody. Single hybridoma cells are cloned to produce many identical cells that all produce the same antibody. A large amount of the antibody can be collected and purified. |
Producing Monoclonal Antibodies |
4.3.2-lo-2 |
4.3.2.2 Students should be able to describe some of the ways in which monoclonal antibodies can be used. 4.3.2.2 Some examples include: 4.3.2.2 • for diagnosis such as in pregnancy tests 4.3.2.2 • in laboratories to measure the levels of hormones and other chemicals in blood, or to detect pathogens 4.3.2.2 • in research to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye 4.3.2.2 • to treat some diseases: for cancer the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. It delivers the substance to the cancer cells without harming other cells in the body. 4.3.2.2 Students are not expected to recall any specific tests or treatments but given appropriate information they should be able to explain how they work. 4.3.2.2 Monoclonal antibodies create more side effects than expected. They are not yet as widely used as everyone hoped when they were first developed. |
Uses and Limits |
Producing Monoclonal Antibodies¶
- A mouse is first stimulated to produce lymphocytes that make a desired antibody. These lymphocytes are then fused with tumour cells to make hybridoma cells.
- Hybridoma cells divide rapidly like tumour cells but keep the ability to make one specific antibody like the original lymphocyte.
- Cloning the hybridoma produces large amounts of identical antibody, which can then be collected and purified.
Uses and Limits¶
- Monoclonal antibodies can be linked to dyes or radioactive substances to locate specific molecules or cells in the body.
- They are used in pregnancy tests, laboratory tests and some cancer treatments because they can be designed to bind to a chosen target.
- Like any medical treatment, they can have side effects, so benefits have to be balanced against risks.
Common Confusions¶
- Monoclonal vs. polyclonal antibodies: Monoclonal comes from one cell clone and targets one epitope (one specific part of an antigen). Polyclonal (from natural immune response) includes many different antibodies targeting different parts of the same antigen.
- Why fuse with tumour cells: Normal lymphocytes can make antibodies but divide only a few times. Tumour cells divide forever but don't make antibodies. Hybridomas combine both abilities.
- Cloning: Making clones of hybridoma cells produces identical cells that make identical antibody. This is cloning of cells, not cloning of whole organisms.
Key Terms¶
- Monoclonal antibody: an antibody produced from a single clone of cells and therefore all identical.
- Polyclonal antibody: a mixture of different antibodies, each targeting different parts of an antigen.
- Hybridoma: a cell formed by fusing a lymphocyte with a tumour cell.
- Lymphocyte: a type of white blood cell that produces antibodies.
- Specificity: the property of binding to one particular target and not others.
- Antigen: a molecule recognised by the immune system as foreign or targetable.
- Epitope: a specific part of an antigen that an antibody binds to.
- Pregnancy test: a test that uses monoclonal antibodies to detect a hormone (hCG) linked to pregnancy.