Summary
An antigen selects the lymphocyte that recognises it, which multiplies into effector and memory clones.
In depth
Burnet's theory: each lymphocyte has a unique receptor made before antigen exposure. Antigen binding selects matching cells to expand into clones. Self-reactive clones are eliminated.
Explains specificity and memory.
It is the basis for immunological memory and explains why the response is specific. Each lymphocyte carries only one receptor type.
Remember: selection happens by antigen, not by the immune system 'designing' antibodies.
The theory was proposed by Burnet in 1957 building on Jerne and Talmage, and explains specificity, memory and tolerance. Each lymphocyte displays a single receptor type, so antigen picks out the right clone from millions. Lymphocytes with strong reactivity to self are eliminated or inactivated during development (clonal deletion).
Proliferation can produce millions of daughter cells in days. Evidence includes the fact that antigens do not instruct antibodies, and that depleting lymphocytes with radiolabelled antigens blocks specific responses. It is also the logic behind monoclonal antibodies, which come from a single clone.
Common mistake: thinking the antigen causes B cells to make a specific antibody; the antigen only selects among existing cells.
Frequently asked questions
What is Clonal Selection?
An antigen selects the lymphocyte that recognises it, which multiplies into effector and memory clones.
Which area of biology covers Clonal Selection, and how advanced is it?
Clonal Selection is one of the 52 topics in Immunology & Disease. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Adaptive Immunity, B Lymphocytes, Vaccines.
Can you give an example of Clonal Selection?
After infection, the number of specific T cells can increase thousand-fold.
What should I learn before Clonal Selection?
Work through the Beginner topics in Immunology & Disease first, such as Immune System, Viruses, Innate Immunity, then return to Clonal Selection. Intermediate topics assume the Beginner vocabulary.
What topics are related to Clonal Selection?
The closest topics to Clonal Selection are Adaptive Immunity, B Lymphocytes, Vaccines, Antibodies. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Clonal Selection?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Clonal Selection. To practise the whole of Immunology & Disease, use the Immunology & Disease quiz.
How is Clonal Selection different from Adaptive Immunity?
Clonal Selection: An antigen selects the lymphocyte that recognises it, which multiplies into effector and memory clones. Adaptive Immunity: Slower, specific defence involving lymphocytes that remember pathogens. Read both side by side and note what each one explains.
What is a common mistake about Clonal Selection?
Thinking the antigen causes B cells to make a specific antibody; the antigen only selects among existing cells.
How should I study Clonal Selection step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Adaptive Immunity and explain the difference aloud. Finally, take the Immunology & Disease quiz and come back to this page for any question you miss.