Antigen vs. Immunogen

In immunology, an antigen (Ag) is a molecule or molecular structure, such as may be present on the outside of a pathogen, that can be bound by an antigen-specific antibody or B-cell antigen receptor. The presence of antigens in the body normally triggers an immune response.

An immunogen is an antigen or any substance that may be specifically bound by components of the immune system (antibody, lymphocytes). The term antigen arises from its ability to induce generation of antibodies.

a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.

An antigen that is capable of inducing an immune response.

A molecule that is capable of binding to an antibody or to an antigen receptor on a T cell, especially one that induces an immune response. An antigen is usually a foreign substance, such as a toxin or a component of a virus, bacterium, or parasite.

(immunology) Any substance that elicits a immune response; an antigen

(immunology) A substance that induces an immune response, usually foreign.

any substance that produces immunity when introduced into the body.

any substance (as a toxin or enzyme) that stimulates the production of antibodies

any substance or organism that provokes an immune response (produces immunity) when introduced into the body