B2 noun Formal

antigen

/ˈæntɪdʒən/

An antigen is any substance, such as a toxin, virus, or bacterium, that causes the body's immune system to produce antibodies against it. It is essentially a chemical marker that the body recognizes as foreign or harmful.

Examples

3 of 5
1

The doctor explained that the antigen in the vaccine would help my body prepare for future infections.

The physician clarified that the substance in the shot triggers the body to prepare for later illnesses.

2

The presence of a specific viral antigen indicates an active infection within the patient.

Finding a particular viral marker shows the patient currently has the disease.

3

Think of an antigen as a 'wanted poster' that tells your immune system who the bad guys are.

Consider this substance a signal that identifies threats to your body's defenses.

Word Family

Noun
antigen, antigenicity
Adverb
antigenically
Adjective
antigenic
Related
antibody
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Memory Tip

Think of 'Anti-gen' as an 'Antibody Generator'. It is the substance that generates the need for antibodies.

Quick Quiz

The patient tested positive for the viral _______, meaning they are likely currently infected.

Correct!

The correct answer is: antigen

Examples

1

The doctor explained that the antigen in the vaccine would help my body prepare for future infections.

everyday

The physician clarified that the substance in the shot triggers the body to prepare for later illnesses.

2

The presence of a specific viral antigen indicates an active infection within the patient.

formal

Finding a particular viral marker shows the patient currently has the disease.

3

Think of an antigen as a 'wanted poster' that tells your immune system who the bad guys are.

informal

Consider this substance a signal that identifies threats to your body's defenses.

4

The study focused on the structural characteristics of the surface antigen of the influenza virus.

academic

The research analyzed the physical traits of the outer markers on the flu virus.

5

The pharmaceutical company is investing heavily in the development of new antigen-based diagnostic kits.

business

The drug firm is funding the creation of testing tools that detect specific biological markers.

Word Family

Noun
antigen, antigenicity
Adverb
antigenically
Adjective
antigenic
Related
antibody

Common Collocations

antigen test a diagnostic procedure to detect viral proteins
surface antigen proteins found on the outer layer of a cell or virus
antigen response the reaction of the immune system to a foreign substance
specific antigen a unique marker belonging to a particular pathogen
antigenic drift the process of small changes in virus genes over time

Common Phrases

antigen-presenting cell

a cell that displays foreign markers to help the immune system recognize them

rapid antigen test

a quick medical test used to detect the presence of specific proteins

antigen-antibody complex

the molecule formed when an antibody binds to its target

Often Confused With

antigen vs antibody

An antigen is the 'invader' or trigger, while an antibody is the 'soldier' produced by the body to neutralize it.

antigen vs pathogen

A pathogen is the entire harmful organism (like a germ), whereas an antigen is a specific part of that pathogen.

📝

Usage Notes

The word is primarily used in medical and biological contexts. While it technically refers to any substance that triggers immunity, in general conversation it is most often used regarding diagnostic tests.

⚠️

Common Mistakes

Learners often use 'antigen' and 'antibody' interchangeably; remember that 'gen' in antigen implies it 'generates' an immune response.

💡

Memory Tip

Think of 'Anti-gen' as an 'Antibody Generator'. It is the substance that generates the need for antibodies.

📖

Word Origin

Derived from the French 'antigène', a contraction of 'antisérum' and 'gène' (producing).

Grammar Patterns

Countable noun (plural: antigens) Often used as a noun adjunct (e.g., antigen detection)
🌍

Cultural Context

The term became widely known by the general public globally during the COVID-19 pandemic due to the prevalence of 'rapid antigen tests'.

Quick Quiz

The patient tested positive for the viral _______, meaning they are likely currently infected.

Correct!

The correct answer is: antigen

Related Words

a

A1

A word used before a singular noun that is not specific or is being mentioned for the first time. It is used only before words that begin with a consonant sound to indicate one of something.

I

A1

The pronoun 'I' is used by a speaker or writer to refer to themselves as the subject of a verb. It is the first-person singular subject pronoun in English and is always capitalized regardless of its position in a sentence.

for

A1

Used to show who is intended to have or use something, or to explain the purpose or reason for an action. It is also frequently used to indicate a specific duration of time.

not

A1

A function word used to express negation or denial. It is primarily used to make a sentence or phrase negative, often following an auxiliary verb or the verb 'to be'.

with

A1

A preposition used to indicate that people or things are together, in the same place, or performing an action together. It can also describe the instrument used to perform an action or a characteristic that someone or something has.

he

A1

A pronoun used to refer to a male person or animal that has already been mentioned or is easily identified. It functions as the subject of a sentence.

you

A1

Used to refer to the person or people that the speaker is addressing. It is the second-person pronoun used for both singular and plural subjects and objects.

at

A1

A preposition used to indicate a specific point, location, or position in space. It is also used to specify a particular point in time or a certain state or activity.

but

A1

A coordinating conjunction used to connect two statements that contrast with each other. It is used to introduce an added statement that is different from what has already been mentioned.

his

A1

This word is used to show that something belongs to or is associated with a male person or animal previously mentioned. It functions as both a possessive determiner used before a noun and a possessive pronoun used on its own.

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