Antigens
Antigens (pronounced: /ˈan(t)əˌjen/) are substances that can trigger an immune response in the body, particularly in the production of antibodies. The term "antigen" is derived from the words "antibody" and "generator".
Definition
An Antigen is a molecule capable of inducing an immune response on the part of the host organism. They are usually proteins or polysaccharides. This includes parts (coats, capsules, cell walls, flagella, fimbriae, and toxins) of bacteria, viruses, and other microorganisms.
Types of Antigens
There are several types of antigens, including:
- Exogenous Antigens: These antigens enter the body from the outside, for example during inhalation, ingestion, or skin penetration.
- Endogenous Antigens: These are generated within normal cells as a result of normal cell metabolism, or because of viral or intracellular bacterial infection.
- Autoantigens: An autoantigen is usually a normal protein or complex of proteins (and sometimes DNA or RNA) that is recognized by the immune system of patients suffering from a specific autoimmune disease.
Antigen Presentation
Antigen Presentation is a process in the body's immune system by which macrophages, dendritic cells, and other cell types capture antigens and then enable their recognition by T-cells.
Antigen-Antibody Interaction
The specific interaction between an Antigen and an Antibody triggers an immune response. The part of the antigen that the antibody binds to is called the Epitope or antigenic determinant.
Related Terms
- Immunogen: An immunogen is an antigen substance (or adduct) that evokes an immune response.
- Allergen: An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body.
- Superantigen: Superantigens are a class of antigens that result in excessive activation of the immune system.
See Also
External links
- Medical encyclopedia article on Antigens
- Wikipedia's article - Antigens
This WikiMD dictionary article is a stub. You can help make it a full article.
Languages: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
Urdu,
বাংলা,
తెలుగు,
தமிழ்,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
European
español,
Deutsch,
français,
русский,
português do Brasil,
Italian,
polski