The multiple mechanisms and processes through which the body identifies and reacts to antigens. The immune response is the body’s primary means of protecting itself from INFECTION. There are three independent yet complementary immune response pathways: ANTIBODYMEDIATED IMMUNITY (also called humoral immunity), CELL-MEDIATED IMMUNITY, and the COMPLEMENT CASCADE. As well, the immune response stimulates activity from the NERVOUS SYSTEM and the endocrine system.
The immune response relies largely on ANTIBODY-ANTIGEN binding. Antigens are molecules that identify cells to the IMMUNE SYSTEM. Antibodies are molecules the immune system produces to bind with nonself antigens-antigens on cells that do not belong to the body. With antibody-antigen binding, the antibody releases proteins called opsonins that mark the antigen-bearing cell for destruction by killer T-cells and natural killer (NK) cells. Monocytes (in the BLOOD circulation) and macrophages (in the tissues) consume the cellular debris remaining after the marked cell’s destruction. Antibody-antigen binding also activates the complement cascade, a biochemical response that produces proteins that attach to and damage the cell membrane of cells that the immune response identifies as nonself.
A key feature of the immune response is INFLAMMATION, the process by which the body increases the ability of PLASMA, the liquid component of blood, to seep into the tissues (interstitial spaces). HISTAMINE and PROSTAGLANDINS are the primary agents of the inflammatory response. Inflammation floods the tissues with immune molecules to extend the immune response beyond the blood and the LYMPH. Inflammation also serves to contain the infection, keeping it from spreading beyond its point of origin to other areas of the body.
For further discussion of the immune response within the context of the structures and functions of the immune system, please see the overview section “The Immune System and Allergies.”
See also ALLERGEN; ECHINACEA; GOLDENSEAL; HUMAN LEUKOCYTE ANTIGENS (HLAS); HYPERSENSITIVITY REACTION; MACROPHAGE; MAJOR HISTOCOMPATIBILITY COMPLEX (MHC); MAST CELL; MONOCYTE; NATURAL KILLER (NK) CELLS; PHAGOCYTOSIS.
Resource: Facts On File Encyclopedia Of Health And Medicine
Antibody definition Antibody is a unique molecule that binds with a specific ANTIGEN so the IMMUNE SYSTEM can neutralize or destroy the antigen. Antigens are molecular markers on the surfaces of cells that identify the cells to the immune system. Antibodies are the immune system’s infantry, patrolling the BLOOD and LYMPH circulations and responding
Allergy definition Allergy - an abnormal sensitivity to an ordinarily harmless substance, called an ALLERGEN, that produces a HYPERSENSITIVITY REACTION (allergic reaction) in response to the IMMUNE SYSTEM’s detection of the substance’s presence. A person can have an allergy to nearly any substance. Though researchers understand the mechanisms
Diagnostic procedures to determine the allergens responsible for HYPERSENSITIVITY REACTION. The most specific ALLERGY test is the allergy SKIN test, also called a scratch test or a patch test. For this test, the allergist uses the inside of the arm or a section of the back to expose the body to suspected allergens. The allergist places a small drop of a
A HYPERSENSITIVITY REACTION (allergic reaction) that affects the SKIN, usually in response to contact with an ALLERGEN. As with all hypersensitivity reactions, the first exposure to the allergen produces no symptoms. In reaction to the exposure, however, the IMMUNE SYSTEM produces antibodies for the allergen. Subsequent exposures to the allergen then do
What is Allergic Asthma and definition Allergic asthma is a HYPERSENSITIVITY REACTION (allergic reaction) that involves the airways (bronchi). allergic ASTHMA is a type I or IMMUNOGLOBULIN E (IgE) reaction. Mast cells in the bronchial membranes release HISTAMINE, PROSTAGLANDINS, and LEUKOTRIENES. These substances cause itching and swelling of the bronchial
Allergic conjunctivitis - A type I (IMMUNOGLOBULIN E [IgE]) HYPERSENSITIVITY REACTION, commonly called an allergic reaction, that affects the membranes that line the inner eyelids (conjunctiva). Sometimes the irritation also reddens the white part of the eye (sclera). Allergic CONJUNCTIVITIS features red and swollen conjunctiva with excessive tearing and
Define Active Immunity Long-term, acquired immune protection. Active immunity, also called acquired immunity, results from fighting an INFECTION or receiving a VACCINE that stimulates ANTIBODY response. In many circumstances active immunity is lifelong.
At birth the IMMUNE SYSTEM is fairly undeveloped. The infant relies largely on the carryover of maternal immune components for about the first six weeks of its life, while the infant’s body builds its own immune system. By age four months, maternal IMMUNITY wears off and the infant’s immune system is on its own (though an infant who is
What is Allergen and definition Allergen - a harmless substance, also called a hapten, that causes an exaggerated response from the IMMUNE SYSTEM called a HYPERSENSITIVITY REACTION. For reasons researchers do not fully understand, the immune system produces antibodies for the substance that result in the IMMUNE RESPONSE perceiving the substance as a
What is Allergic Rhinitis and Definition A HYPERSENSITIVITY REACTION to inhaled allergens. Allergic rhinitis, also called seasonal rhinitis or hay FEVER, affects the mucous membranes inside the NOSE (nasal mucosa). Allergic rhinitis affects about 40 million adults in the United States, making it one of the most common hypersensitivity reactions. The