Canadian Medical Guide > Chemicals and Drugs > Immunologic and Biological Factors > Immunologic Factors > Antigens Terms and Definitions

Antigens

Medical Definition:	Substances that are recognized by the immune system and induce an immune reaction.
Guide Notes:	GEN or unspecified: prefer specifics

Antigens Categories.

	Allergens - Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).
	Antigens, Archaeal - Substances of archaeal origin that have antigenic activity.
	Antigens, Bacterial - Substances elaborated by bacteria that have antigenic activity.
	Antigens, Dermatophagoides - Antigens from the house dust mites (DERMATOPHAGOIDES), mainly D. farinae and D. pteronyssinus. They are proteins, found in mite feces or mite extracts, that can cause ASTHMA and other allergic diseases such as perennial rhinitis (RHINITIS, ALLERGIC, PERENNIAL) and atopic dermatitis (DERMATITIS, ATOPIC). More than 11 groups of Dermatophagoides ALLERGENS have been defined. Group I allergens, such as Der f I and Der p I from the above two species, are among the strongest mite immunogens in humans.
	Antigens, Fungal - Substances of fungal origin that have antigenic activity.
	Antigens, Helminth - Any part or derivative of a helminth that elicits an immune reaction. The most commonly seen helminth antigens are those of the schistosomes.
	Antigens, Heterophile - Antigens stimulating the formation of, or combining with heterophile antibodies. They are cross-reacting antigens found in phylogenetically unrelated species.
	Antigens, Neoplasm - Proteins, glycoprotein, or lipoprotein moieties on surfaces of tumor cells that are usually identified by monoclonal antibodies. Many of these are of either embryonic or viral origin.
	Antigens, Protozoan - Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.
	Antigens, Surface - Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.
	Antigens, T-Independent - Antigens which may directly stimulate B lymphocytes without the cooperation of T lymphocytes.
	Antigens, Viral - Substances elaborated by viruses that have antigenic activity.
	Autoantigens - Endogenous tissue constituents that have the ability to interact with AUTOANTIBODIES and cause an immune response.
	Epitopes - Sites on an antigen that interact with specific antibodies.
	Isoantigens - Antigens that exist in alternative (allelic) forms in a single species. When an isoantigen is encountered by species members who lack it, an immune response is induced. Typical isoantigens are the BLOOD GROUP ANTIGENS.
	Superantigens - Microbial antigens that have in common an extremely potent activating effect on T-cells that bear a specific variable region. Superantigens cross-link the variable region with class II MHC proteins regardless of the peptide binding in the T-cell receptor's pocket. The result is a transient expansion and subsequent death and anergy of the T-cells with the appropriate variable regions.

Antigens Medical Definitions and Terms

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