Words / B2

ANT-ij-uh-n/ˈæntɪdʒən/

An antigen is a substance that the immune system treats as foreign and may make antibodies against: a surface antigen; antigen test. Antibody is the matching protein (this batch); pathogen is a disease-causing organism, not every antigen; allergen is an antigen that triggers allergy. Name the antigen in the blood-group practical, then the reaction. Mix-up: antigen vs antique; again; do not write antigen for a named vitamin unless the source says it is immunogenic.

Meaning

A substance that the immune system treats as foreign and may make antibodies against.

Examples

• “Name the antigen in the blood-group practical, then the reaction, the biology paper said.”
• “An antigen test featured in the public-health table, which is the diagnostic sense — still quote the n and the date.”

Good to know

a surface / viral antigen; antigen test; blood-group antigens. Pair: antibody. Close: allergen / pathogen (related, not identical). Trap: antique. Biology and PSHE. A substance that triggers an immune response — name it and the reaction.

Near in meaning

immunogen, surface marker, allergen

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