🧬 The lymphocyte
The lymphocyte brings the ability to make the particular antibody that we want.
Monoclonal Antibodies » Monoclonal Antibodies
What you'll learn this session
Study time: 30 minutes
AQA spec: 4.3.2.1, 4.3.2.2
- What monoclonal antibodies are and why they target one thing only
- How monoclonal antibodies are produced, step by step
- How they are used in diagnosis, laboratories, research and treating disease
- Why they are not yet as widely used as people hoped
Higher tier only. This lesson is also for Biology only (not Combined Science).
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Unlock This CourseWhat are monoclonal antibodies?
Your white blood cells make antibodies to fight pathogens. Each antibody fits one particular shape on a pathogen. Scientists have learned how to make large amounts of one single type of antibody on purpose. These are called monoclonal antibodies.
The word "monoclonal" tells you how they are made. "Mono" means one, and the antibodies all come from a single clone of cells. A clone is a group of identical cells, all copied from one original cell. So every antibody they make is exactly the same.
These antibodies are very specific. Each one fits one binding site on one protein antigen. This means a monoclonal antibody can target one particular chemical, or one particular type of cell in the body, and ignore everything else.
Key terms:
- Monoclonal antibody: an antibody made from a single clone of cells, specific to one binding site on one protein antigen.
- Antigen: a protein on the surface of a cell or pathogen that an antibody can bind to.
- Binding site: the part of the antigen that the antibody attaches to.
- Lymphocyte: a type of white blood cell that makes antibodies.
- Hybridoma cell: a cell made by combining a lymphocyte with a tumour cell. It can both divide and make an antibody.
How are monoclonal antibodies produced?
You need to be able to describe this process. Learn the steps in order.
- Stimulate: mouse lymphocytes are stimulated to make a particular antibody.
- Combine: the lymphocytes are combined with a particular kind of tumour cell. This makes a hybridoma cell.
- Clone: single hybridoma cells are cloned to produce many identical cells. They all produce the same antibody.
- Collect and purify: a large amount of the antibody can be collected and purified.
🧠 The tumour cell
The tumour cell brings the ability to divide. Joined together, the hybridoma cell can both divide and make the antibody.
Uses of monoclonal antibodies
Because they target one thing so precisely, monoclonal antibodies have many uses. You are not expected to recall specific tests or treatments. Given information about one, you should be able to explain how it works.
📋 Diagnosis
Monoclonal antibodies are used for diagnosis, such as in pregnancy tests.
🧪 In laboratories
They are used to measure the levels of hormones and other chemicals in blood, or to detect pathogens.
🔬 In research
They are used to locate or identify specific molecules in a cell or tissue, by binding to them with a fluorescent dye.
💉 Treating disease
For cancer, the antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing.
How do they treat cancer?
A monoclonal antibody can be made to target specific cells in the body, such as cancer cells.
The antibody is bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. It acts like a delivery van with an exact address. It delivers the substance to the cancer cells without harming other cells in the body.
Worked example: explaining a test
A test uses monoclonal antibodies that bind only to hormone X. Why does the test not react to other hormones? Because the monoclonal antibodies are specific to one binding site on one antigen, so they cannot bind to other chemicals. They only bind to hormone X, so the test detects that hormone and nothing else.
Evaluating monoclonal antibodies
Monoclonal antibodies create more side effects than expected. They are also not yet as widely used as everyone hoped when they were first developed. When you evaluate them, put the advantages and disadvantages side by side:
✅ Advantages
Very specific, so they can target one chemical or one type of cell. In cancer treatment they deliver the substance without harming other cells in the body.
⚠ Disadvantages
More side effects than expected, and not as widely used as everyone hoped.
Common mistakes
Saying that the antibodies are made by tumour cells alone. They are made by hybridoma cells, which come from a lymphocyte combined with a tumour cell. Also, do not forget that the antibody in cancer treatment is a carrier: it delivers a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing.
Exam-style question
(a) Describe how monoclonal antibodies are produced. [4 marks]
(b) A toxic drug is attached to a monoclonal antibody to treat cancer. Explain why this is better than giving the toxic drug alone. [2 marks]
Model answer
(a) Mouse lymphocytes are stimulated to make a particular antibody (1). The lymphocytes are combined with a tumour cell to make a hybridoma cell (1). Single hybridoma cells are cloned to produce many identical cells (1). A large amount of the antibody is collected and purified (1).
(b) The antibody is specific to the cancer cells (1), so it delivers the drug to the cancer cells without harming other cells in the body (1).
Exam tip
For a "describe how they are produced" question, give the steps in order and use the words "lymphocyte", "hybridoma" and "cloned". Each one is usually a mark point.