Allergy Dictionary

Table of Contents

Adrenaline (or epinephrine) is a hormone produced by the kidneys in response to an emergency situation anaphylaxis . Adrenaline makes the heart beat faster, narrows the blood vessels and dilates the airways.

A protein molecule (antigen) that can trigger the immune system to produce antibodies and thereby cause an allergic reaction. Examples are proteins in pollen, house dust mites and animal dander (dead skin cells).

Allergen extract
A fluid containing allergens extracted from natural sources (e.g. trees, grass, cat hair and dander) to a defined standard, quality and quantity. Used in specific allergy vaccination, skin prick tests, provocation tests and in vitro tests.

Hypersensitivity of the immune system to a natural substance that does not cause symptoms in non-allergic people. Examples of allergic illnesses are hay fever, urticaria, asthma and contact dermatitis. Allergy can be seasonal – e.g. allergy to pollen (hay fever) – or occur all year round – e.g. allergy to animals or dust.

Also known as anaphylactic shock. An acute allergic reaction. Symptoms occur immediately after exposure to an allergen (e.g. insect stings) and include diarrhea, bleeding, vomiting, bronchospasm and breathing problems. If you experience these or similar symptoms, seek immediate medical assistance, because anaphylaxis can cause loss of consciousness and even death. Anaphylactic reactions can be reversed with adrenaline. If you have already experienced an anaphylactic shock, consider starting specific allergy vaccination and always carry a device containing adrenaline (e.g EpiPen).

Antibodies (or immunoglobulins) are proteins in blood and body fluid. Antibodies are produced by B-cells when these are triggered by an allergen. Antibodies recognise foreign substances (e.g. bacteria) and bind to their surface, thereby helping the immune system to destroy them. There are five different classes of antibodies. Immunoglobulin E IgE is of importance in allergy.

See allergen.

Antihistamine drugs
Histamine is released by mast cells in body tissue as a response to an allergen and gives rise to the symptoms of an allergic response. Antihistamine drugs influence (reduce) the release of histamine. Antihistamine drugs come in various forms (liquid or powder for the nose, eye drops or tablets) and can provide instant relief from the symptoms, depending on the severity of the attack.

A chronic lung disease characterised by inflammation which destroys lung tissue and by contraction of the smooth muscles cells lining the bronchi, making it difficult to breathe. Asthma can be either allergic or non-allergic.

B-cells (or B-lymphocytes) are white blood cells that produce and secrete antibodies into the blood. See also Cell memory.

Inflammation in the bronchi, resulting in coughing and the production of sputum. Can be caused either by an infection or an allergy.

The branching airways of the lungs.

Causal treatment
A form of treatment which deals with the cause of a disease, not only the symptoms. Specific allergy vaccination is a causal treatment, the use of antihistamines is a symptomatic treatment.

Cell memory
If foreign substances (e.g. bacteria) enter the body, the immune system reacts by attacking and killing them. At the same time, T-cells and B-cells produce a population of memory cells. If you are subsequently exposed to the same bacteria, the immune system reacts much more quickly. In allergy, this mechanism is called “priming”. You do not experience an allergic reaction the first time you are exposed to a particular allergen, but your body registers the allergen and, over time, you may develop an allergy to it.

Challenge test
See Provocation test

Contact dermatitis
A rash or inflammation of the skin. As the term indicates, you develop an allergy to something that comes into contact with your skin. Many things in everyday life can provoke contact dermatitis – e.g. rubber gloves or the nickel in your buttons or watch.

Corticosteroid drugs
Anti-inflammatory drugs that interfere with the immune system, suppress it and thereby dampen the inflammatory overreaction. They can be used to treat a number of allergic diseases – e.g. allergic rhinitis, eczema and rheumatoid arthritis. Corticosteroid drugs come as creams, inhalants, tablets and eye drops.

Skin disorder causing reddening, itching, swelling and scaling. Can occur for various reasons, including exposure to allergens.

See Adrenaline

Hay fever
See Rhinitis.

A biologically active substance released from mast cells during an allergic reaction in response to an allergen. Histamine causes running nose, sneezing and itching, and narrows the airways in the lungs. Antihistamines can be used to block the release of histamine that would otherwise occur as a result of exposure to an allergen.

See Urticaria.

See specific allergy vaccination.

See Corticosteroid drugs

IgE (ImmunoglobulinE) is the antibody produced in excess in allergic patients. IgE can be measured in a blood sample to determine if a person is allergic. Allergic people usually have high levels of IgE.

Immune system
A system of organs that react to foreign agents (e.g. bacteria, virus and moulds), thereby protecting the body. The immune system consists of thymus, bone marrow, lymph nodes and spleen. In allergic people, the immune system overreacts to harmless agents.

See Antibody.

See specific allergy vaccination.

A reaction to an injury to the body – by infection, chemicals or physical agents. The symptoms can be – depending on the location of the injury- redness, swelling, heat and pain. The purpose of the inflammation is to dilute and destroy the agent causing the inflammation. To do this, the immune system starts a cascade of actions that causes active cells to gather at the affected location. It is these cells and fluids that cause the redness, swelling, heat and pain.

Messenger molecule between the different cells of the immune system.

When the body reacts inappropriately but non-allergically (i.e. without IgE production) to a particular substance. Many people experience reactions to certain types of food. Of these, 2-3% are allergic to the foods concerned; the rest experience intolerance.

Intracutan test
Intracutan tests are used to diagnose allergies. A small amount of allergen extract is injected under the skin on your arm. If the area becomes itchy, reddish and swelling you may have an allergy.

In vitro
What goes on in a test tube, e.g. IgE determination in a blood sample. The opposite of in vivo.

In vivo
In vivo means ‘in the living organism’, i.e. examination of the living organism – for example, a skin prick test.

A large cell that acts as a scavenger, helping the immune system to destroy foreign agents.

Mast cell
Mast cells are found all over the body, especially in connective tissue such as the skin. When exposed to an allergen, the mast cell releases histamine and other related substances.

PEF (Peak Expiratory Flow)
A measurement of lung function, established by the patient’s blowing into a special device. The higher the number recorded, the better the lung function. PEF is dependent on the severity of the disease, gender, age and height. A lower reading than expected may be caused by an allergy.

Pollen is the male fertilising agent of flowering plants, grasses, trees and weeds.

Provocation test
Also called a challenge test. A test performed on eyes, nose or lungs and used to diagnose an allergy or monitor the effect of e.g. specific allergy vaccination. The allergen is introduced in increasing doses to the organ to see if the person reacts and, if so, at what level of exposure.

Rhinitis is inflammation of the cells lining the nose resulting from the inhalation of an allergen. The symptoms include nasal obstruction, runny nose and sneezing. Rhinitis can be seasonal, e.g. allergy to pollen (hay fever), or all yearround – e.g. allergy to animals or dust.

Skin prick test
Skin prick tests are used to diagnose allergies. Pricking gently through a drop of allergen extract placed on the surface of the arm may result after 10-15 minutes in the appearance of a small, itchy swelling and a reddening of the skin. This indicates an allergy.

Specific allergy vaccination
Specific allergy vaccination is also called specific immunotherapy, hyposensitisation or allergy shot. It is a vaccination programme that affects the natural course of an allergic disease, not only its symptoms. When the patient is given increasing doses of the allergen to which he or she is allergic, the immune system becomes less sensitive and the patient no longer reacts. Two different types of vaccine exist: a depot (slow-release) preparation and an aqueous solution.

See specific allergy vaccination.

See corticosteroid drugs

Symptomatic treatment
A treatment with drugs that only affects the symptoms of the disease, not its cause – e.g. antihistamines and corticosteroids.

T-cells or T-lymphocytes (white blood cells) determine together with interleukins which class of antibodies is to be produced by the B-cells. See also Cell memory.

Urticaria, also called “hives”, is an inflammation of the skin – an itchy rash.

ß2-agonists are used in the treatment of asthma and chronic obstructive lung disease (COPD) and are used to relax the smooth muscles in the bronchi, which contract during an asthma attack. ß2-agonists are available in short-acting and long-acting formulations for inhalation and as tablets.