Allergy Dictionary


Section Jump: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U-Z


A

Adrenaline: Epinephrine (also known as adrenaline) is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system.

Allergen: An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals.

Allergen extract: This is what comprises "allergy injections." The extract is a combination of allergens that are placed in a vial and used for injections.

Allergy: An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid. Allergy is one of four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity. Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E (IgE). This reaction results in an inflammatory response which can range from uncomfortable to dangerous.

Allergen immunotherapy: Allergen immunotherapy (also termed hyposensitization therapy, immunologic desensitization, hyposensibilization, or allergen-specific immunotherapy) is a form of immunotherapy for allergic disorders in which the patient is vaccinated with increasingly larger doses of an allergen (substances to which they are allergic) with the aim of inducing immunologic tolerance.

Anaphylaxis: Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including an itchy rash, throat swelling, and low blood pressure. Common causes include insect bites, foods, and medications.

Antibody: An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen.

Antigen: An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader.

Antihistamine drugs: Antihistamine drugs are medications used to combat allergy such as Zyrtec, Claritin, Allegra, cetirizine, or Benadryl. Each antihistamine has two names, the generic and the trade name.

Asthma: Asthma (from the Greek άσθμα, ásthma, "panting") is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath.

B

B-cell: B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by T cells). The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells (APCs) and eventually develop into memory B cells after activation by antigen interaction. B cells are an essential component of the adaptive immune system.

Bronchitis: Bronchitis is inflammation of the mucous membranes of the bronchi, the airways that carry airflow from the trachea into the lungs. Bronchitis can be divided into two categories, acute and chronic, each of which has unique etiologies, pathologies, and therapies.

Bronchi: A bronchus (plural bronchi, adjective bronchial) is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles. No gas exchange takes place in this part of the lungs.

C

Cell memory: Cells in the immune system "remember" infections that they come in contact with throughout your lifetime. This process is called cell memory.

Challenge test: Often foods, medications (aspirin is well known), and other substances cause adverse reactions and to identify these agents, allergists perform a challenge test. This occurs by giving patients very small doses and increasing the dose over 3-4 hours. Symptoms are carefully monitored during the procedure. Often this test is most useful when skin testing is negative.

Contact dermatitis: Contact dermatitis is a term for a skin reaction (dermatitis) resulting from exposure to allergens (allergic contact dermatitis) or irritants (irritant contact dermatitis). Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight.

Corticosteroid drugs: Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior.

E

Eczema: Eczema (From Greek ἔκζεμα ēkzema, 'to boil over') is a form of dermatitis, or inflammation of the epidermis (the outer layer of the skin).

Epinephrine: Epinephrine (also known as adrenaline) is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system.

H

Hay fever: Allergic rhinitis, also known as pollenosis or hay fever, is an allergic inflammation of the nasal airways. It occurs when an allergen, such as pollen, dust or animal dander (particles of shed skin and hair) is inhaled by an individual with a sensitized immune system. In such individuals, the allergen triggers the production of the antibody immunoglobulin E (IgE), which binds to mast cells and basophils containing histamine.

Histamine: Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by basophils and by mast cells found in nearby connective tissues. Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.

Hives: See Urticaria

Hyposensitisation: Allergen immunotherapy (also termed hyposensitization therapy, immunologic desensitization, hyposensibilization, or allergen-specific immunotherapy) is a form of immunotherapy for allergic disorders in which the patient is vaccinated with increasingly larger doses of an allergen (substances to which they are allergic) with the aim of inducing immunologic tolerance. Allergen specific immunotherapy is the only treatment strategy which treats the underlying cause of the allergic disorder. It is a highly cost-effective treatment strategy which results in an improved quality of life and a reduction in allergic- and allergen-related asthma, as well as a reduction in days off school/work. Immunotherapy has been shown to produce long-term remission of allergic symptoms, reduce severity of associated asthma, as well as reduce the chances of new sensitizations to allergens developing. This is achieved via immunotherapy modulating the immune system response to allergens.

Hydrocortisone: Cortisol (hydrocortisone) is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland.[1] It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat, protein and carbohydrate metabolism.[1] It also decreases bone formation. During pregnancy, increased production of cortisol between weeks 30-32 initiates production of fetal lung surfactant to promote maturation of the lungs. Various synthetic forms of cortisol are used to treat a variety of diseases.

I

IgE: Immunoglobulin E (IgE) is a class of antibody (or immunoglobulin "isotype") that has been found only in mammals. It plays an important role in allergy, and is especially associated with type 1 hypersensitivity.

Immune system: An immune system is a system of biological structures and processes within an organism that protects against disease. In order to function properly, an immune system must detect a wide variety of agents, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.

Immunoglobulins: An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen.

Immunotherapy: Immunotherapy is a medical term defined as the "treatment of disease by inducing, enhancing, or suppressing an immune response". Immunotherapies designed to elicit or amplify an immune response are classified as activation immunotherapies. While immunotherapies that reduce or suppress are classified as suppression immunotherapies.

Inflammation: Inflammation (Latin, īnflammō, "I ignite, set alight") is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants.

Interleukin: Interleukins are a group of cytokines (secreted proteins/signaling molecules) that were first seen to be expressed by white blood cells (leukocytes). The term interleukin derives from (inter-) "as a means of communication", and (-leukin) "deriving from the fact that many of these proteins are produced by leukocytes and act on leukocytes".

Intolerance: Some reactions to foods and medications cause symptoms of headache or "not feeling well." The mechanism of this adverse reaction doesn't show up on skin testing and allergists call this type of reaction an "intolerance." Examples of an intolerance include: headache after exposure to cleaning agents; diarrhea after eating cheese; skin rash 5 days after starting penicillin antibiotic.

Intracutaneous test: Intradermal skin testing is the same technique. Similar to a TB skin test only with allergen. This type of testing is performed only if prick skin testing is negative. Usually intradermal skin testing is performed on patients older than 8 years old.

In vitro: In vitro (Latin: within glass) refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments are commonly referred to as "test tube experiments".

In vivo: In vivo (Latin for "within the living") is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro ("within the glass", i.e., in a test tube or petri dish) controlled environment.

M

Macrophage: Macrophages (Greek: big eaters, from makros "large" + phagein "eat"; abbr. MΦ) are cells produced by the differentiation of monocytes in tissues.

Mast cell: A mast cell (also known as mastocyte and labrocyte) is a resident cell of several types of tissues and contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense against pathogens.

P

PEF (Peak Expiratory Flow): The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) is a person's maximum speed of expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person's ability to breathe out air. It measures the airflow through the bronchi and thus the degree of obstruction in the airways.

Pollen: Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes (sperm cells).

Provocation test: A provocation test, also called a provocation trial or provocation study, is a form of clinical trial whereby participants are exposed to either a substance or "thing" that is claimed to provoke a response, or to a sham substance or device that should provoke no response. An example of a provocation test, performed on an individual, is a skin allergy test.

R

Rhinitis: Rhinitis commonly known as a stuffy nose, is the medical term describing irritation and inflammation of some internal areas of the nose. The primary symptom of rhinitis is nasal dripping. It is caused by chronic or acute inflammation of the mucous membrane of the nose due to viruses, bacteria or irritants. The inflammation results in the generating of excessive amounts of mucus, commonly producing the aforementioned runny nose, as well as nasal congestion and post-nasal drip.

S

Skin prick test: Skin allergy testing is a method for medical diagnosis of allergies that attempts to provoke a small, controlled, allergic response. A microscopic amount of an allergen is introduced to a patient's skin by various means: Prick test or scratch test: pricking the skin with a needle or pin containing a small amount of the allergen. Patch test: applying a patch to the skin, where the patch contains the allergen

Shots: See Allergen Immunotherapy.

Steroids: See corticosteroid drugs.

Symptomatic treatment: Symptomatic treatment is any medical therapy of a disease that only affects its symptoms, not its cause, i.e., its etiology. It is usually aimed at reducing the signs and symptoms for the comfort and well-being of the patient, but it also may be useful in reducing organic consequences and sequelae of these signs and symptoms of the disease. In many diseases, even in those whose etiologies are known (e.g., most viral diseases, such as influenza), symptomatic treatment is the only one available so far.

T

T-cell: T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T cell receptor (TCR) on the cell surface.

U

Urticaria: Urticaria (or hives) is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes. Most cases of hives lasting less than six weeks (acute urticaria) are the result of an allergic trigger. Chronic urticaria (hives lasting longer than six weeks) is rarely due to an allergy.


β2-adrenergic agonists: β2-adrenergic agonists, also known as β2-adrenergic receptor agonists, are a class of drugs used to treat asthma and other pulmonary disease states. They act on the beta2-adrenergic receptor, thereby causing smooth muscle relaxation, resulting in dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle, and release of insulin.