Antigenität

Antigenität, or antigenicity, is the property of a molecule to be recognized by components of the adaptive immune system, specifically antibodies and T cell receptors, through binding to specific epitopes. It describes the potential of a substance to be detected as foreign and to engage immune receptors. Antigenität can apply to proteins, polysaccharides, lipids linked to proteins, and, in some cases, small molecules that form immunologically relevant structures known as haptens.

Antigenität is distinct from immunogenicität, the ability to provoke a measurable immune response. A substance can be antigenic without being immunogenic, as with haptens that require a carrier protein to elicit antibody production. Immunogenicität depends on processing, presentation, and the activation of B or T cells, not solely on binding to receptors.

The determinants of antigenität include epitopes, the specific molecular features recognized by antibodies or T cell receptors. B cell epitopes are often conformational or linear, while T cell epitopes are presented by MHC molecules. Antigenität is influenced by size, structural complexity, foreignness, stability, and epitope accessibility. Cross-reactivity can occur when different molecules share similar epitopes.

Assessment of antigenität involves binding assays, serological tests, and epitope mapping. Understanding antigenität informs vaccine design, diagnostic assay development, and studies of immune cross-reactivity and autoimmunity. Historically, concepts of antigens and antigenität emerged in the late 19th and early 20th centuries, shaping the modern view of immune recognition and specificity.