antigene

Antigene is a term encountered in immunology and molecular biology. In many contexts, antigene is an older or less common synonym for antigen, the substance that is recognized by the immune system. In current standard usage, antigen is the preferred term, while antigene may be found in historical literature or in non-English texts and may refer to either the whole molecule or to a specific antigenic determinant on a molecule, an epitope. An antigen may be a protein, polysaccharide, lipid, nucleic acid, or a complex composed of subunits; its ability to provoke an immune response is called immunogenicity, whereas its property of binding to specific antibodies or receptors is called antigenicity.

The immune response to an antigen typically involves recognition by B cells and antibodies, and, for peptide antigens, presentation by major histocompatibility complex molecules to T cells. The term epitope denotes the precise molecular feature recognized by an antibody or receptor. Haptenes are small molecules that become antigenic only when bound to a larger carrier molecule, such as a protein.

Antigene therapy is a related but distinct concept in molecular biology and medicine, referring to strategies that aim to suppress gene expression by targeting DNA or RNA with oligonucleotides or other agents. This usage is rare today but appears in some scientific literature as an analogy to antisense or antisense-like approaches.

Antigens are central to vaccines, autoimmune research, and diagnostic tests; they are also used to label samples in immunoassays and to identify immune status. See also antigen, epitope, hapten, and vaccine.