Meaning & use
antigen
Last updated
Meanings
nouncountable
A substance, such as part of a virus or bacterium, that causes the immune system to produce a response against it.
Grammar: Takes a plural: antigens. A core biology and medicine term.
Patterns
- an antigen triggers something
- an antigen test
The spike protein acts as an antigen that the immune system learns to recognize.
Exposure to the antigen caused the body to produce antibodies.
nouncountable
A substance detected in a test designed to show whether a person currently has a particular infection.
Grammar: Used in compounds like antigen test.
Patterns
- a rapid antigen test
- test positive for an antigen
His rapid antigen test came back positive, so he stayed home from work.
Antigen tests are cheaper and faster than PCR tests, though slightly less sensitive.
Word forms
| plural | antigens |
|---|
Common combinations
- viral antigen
- The vaccine presents a harmless viral antigen to train the immune system.
- antigen test
- Passengers were asked to show a negative antigen test before boarding.
- tumor antigen
- Researchers are developing drugs that target specific tumor antigens.
- antigen presentation
- Dendritic cells specialize in antigen presentation to T cells.
Synonyms and how they differ
- immunogen
- A narrower technical term: an antigen that actually provokes an immune response; some antigens are recognized without provoking one.
Opposites
Word family
- antigenic adjective
- Able to act as or relating to an antigen.
- antigenicity noun
- The capacity of a substance to act as an antigen.
Commonly confused: antigen or antibody?
antigen vs antibody
The antigen is the foreign invader that triggers the response; the antibody is the protein the immune system makes to attack it.
Practice
In an immune response, the ___ is the trigger and the ___ is what the body makes to fight it.
Choose one answer.
The antigen is the foreign substance that starts the response, and antibodies are produced against it. Reversing them inverts the roles, and an antibiotic is a medicine, not part of the body's immune response.
Make it your own
Write a sentence using “antigen”, then check it and compare it with the examples above.