Antigenien

Antigenien is not a standard term in contemporary English-language immunology. In some European texts, antigenien may appear as a plural form referring to antigens. The following article uses antigenien in that sense as a reference to the immunogenic substances recognized by the immune system; the concept aligns with the English term antigen.

An antigen is any molecule capable of being recognized by antibodies or T-cell receptors and of eliciting an immune response. Antigenien can be proteins, polysaccharides, lipids, or nucleic acids that contain epitopes—specific molecular structures to which receptors bind. Immunogenicity depends on factors such as foreign origin, molecular size, structural complexity, and the degree to which the molecule is processed and presented by immune cells.

Most antigens are processed by antigen-presenting cells and presented on major histocompatibility complex (MHC) molecules to T cells. B cells can bind intact antigens through surface receptors and, with T helper cell support, generate antibodies. Hapten molecules are too small to provoke an immune response on their own and require linkage to a carrier protein to become antigenic.

Clinical relevance includes vaccines that expose the immune system to specific antigens to induce protection, diagnostic tests that detect antibodies against particular antigens, and conditions such as allergies and autoimmune diseases where immune responses target specific antigens. Understanding antigenien—i.e., antigens—underpins approaches in immunology, vaccinology, and disease diagnostics.