A substance that elicits an antibody response. See also : Allergen

Determinant
Antigenic Determinant

Part of the antigen molecule which binds to an antibody-combining site or to a T-cell receptor ( TCR ).

Epitope

An alternative term for an antigenic determinant. These are particular chemical groups on a molecule that are antigenic, i.e. that elicit a specific immune response.

Hapten

A compound, usually of low molecular weight, that is not itself immunogenic but, when bound to a carrier protein or cell, becomes immunogenic and induces antibodies , which can bind the hapten either alone or in the presence of a carrier.