Common Terms
Glossary of Allergic Terms and Diseases
Allergen: A substance, typically a protein, that elicits an IgE response associated with clinical symptoms
Allergic Reaction: An adverse immunological reaction associated with allergic responses
Allergies: The constellation of clinical problems typically associated with allergic conjunctivitis, allergic rhinitis, asthma and eczema
Allergy: A reaction of the immune system that is triggered by allergens, associated with IgE and is typically harmless to most people
Anaphylaxis: An acute IgE-mediated allergic response that can be life-threatening
Antibody(ies): A protein produced by the body’s immune system that helps neutralize germs by recognizing and binding a specific antigen
Antigen: A substance, typically a protein, that elicits an immune response (such as an antibody)
Asthma: Reversible airway obstruction associated with allergy, typically triggered by aeroallergen exposure
Atopic Dermatitis: Also known as eczema. Dry, itchy skin rash associated with allergies.
Atopy: The predisposition to develop the constellation of allergic diseases including eczema, rhinitis, asthma, and conjunctivitis in individuals with a family history of these problems. This inherited tendency to develop certain allergic hypersensitivity reactions is associated with elevation of IgE
Allergic Reaction: An adverse immunological reaction associated with allergic responses
Allergies: The constellation of clinical problems typically associated with allergic conjunctivitis, allergic rhinitis, asthma and eczema
Allergy: A reaction of the immune system that is triggered by allergens, associated with IgE and is typically harmless to most people
Anaphylaxis: An acute IgE-mediated allergic response that can be life-threatening
Antibody(ies): A protein produced by the body’s immune system that helps neutralize germs by recognizing and binding a specific antigen
Antigen: A substance, typically a protein, that elicits an immune response (such as an antibody)
Asthma: Reversible airway obstruction associated with allergy, typically triggered by aeroallergen exposure
Atopic Dermatitis: Also known as eczema. Dry, itchy skin rash associated with allergies.
Atopy: The predisposition to develop the constellation of allergic diseases including eczema, rhinitis, asthma, and conjunctivitis in individuals with a family history of these problems. This inherited tendency to develop certain allergic hypersensitivity reactions is associated with elevation of IgE
Basophil: A circulating white blood cell that bears IgE receptors, releases histamine and is involve in allergic reactions
Corticosteroid Drugs: A drug of the corticosteroid classification that is typically used for its anti-inflammatory action
DBPC (Double-blind Placebo-controlled) Study: This is a research study in which both the patient and the healthcare provider are unaware of whether the subject is being given the active drug or a placebo (sugar pill) in order to avoid bias in interpretation of the results
Desensitization: Loss of immunological sensitization
Eosinophil(s): A white blood cell that contains granules that absorb the eosin stain
Food Allergies: Allergic reaction to a food substance
Food Challenge: Exposure to a food with the aim of determining whether it will elicit an immunological or clinical response
Gastroesophageal Reflux (GER): Retrograde flow of acidic gastric contents into the esophagus
Corticosteroid Drugs: A drug of the corticosteroid classification that is typically used for its anti-inflammatory action
DBPC (Double-blind Placebo-controlled) Study: This is a research study in which both the patient and the healthcare provider are unaware of whether the subject is being given the active drug or a placebo (sugar pill) in order to avoid bias in interpretation of the results
Desensitization: Loss of immunological sensitization
Eosinophil(s): A white blood cell that contains granules that absorb the eosin stain
Food Allergies: Allergic reaction to a food substance
Food Challenge: Exposure to a food with the aim of determining whether it will elicit an immunological or clinical response
Gastroesophageal Reflux (GER): Retrograde flow of acidic gastric contents into the esophagus
Hay Fever: Seasonal allergic rhinitis caused by exposure to pollen
Histamine: A substance produced by allergic inflammatory cells (mast cells and basophils) that triggers acute allergic symptoms
Hives: A raised and red skin reaction caused by a local or systemic exposure to a substance that is typically triggered by local mast cell activation
House Dust Mite: An insect that lives in dust, typically thrives on human skin flakes and is a potent and common allergen
IgE: Antibody of the E class that is involved in the the development of allergies by triggering mast cells and basophils
IgG: The most common form of protective antibody
Immunotherapy: Manipulation of the immune system to harness a beneficial effect
Inflammation: Swelling of a particular tissue typically caused by the body’s immune response to injury
Interleukin: A hormone in the body that regulates the communication between leukocytes
Histamine: A substance produced by allergic inflammatory cells (mast cells and basophils) that triggers acute allergic symptoms
Hives: A raised and red skin reaction caused by a local or systemic exposure to a substance that is typically triggered by local mast cell activation
House Dust Mite: An insect that lives in dust, typically thrives on human skin flakes and is a potent and common allergen
IgE: Antibody of the E class that is involved in the the development of allergies by triggering mast cells and basophils
IgG: The most common form of protective antibody
Immunotherapy: Manipulation of the immune system to harness a beneficial effect
Inflammation: Swelling of a particular tissue typically caused by the body’s immune response to injury
Interleukin: A hormone in the body that regulates the communication between leukocytes
Leukocytes: White blood cells
Lymphocyte: A leukocyte is characterized by its small nucleus and mononuclear appearance that has a central roll in the adaptive arm (memory response) of the immune system
Macrophage: A leukocyte that is characterized by its ability to engulf (ingest) foreign substances such as bacteria and able to activate lymphocytes
Mast Cells: Leukocytes that have high affinity IgE receptors and are involved in triggering allergies
Natural Killer Cell: A white blood cell involved in killing unwanted cells
Neutrophil: A white blood cell that participates in host defence against bacteria and also is involved in propagating acute inflammation
Patch Test: A skin test that measures delayed reactions to an allergen
Pruritus: Itching
Rhinitis: Nasal congestion
Rhinorrhea: Clear nasal discharge
Lymphocyte: A leukocyte is characterized by its small nucleus and mononuclear appearance that has a central roll in the adaptive arm (memory response) of the immune system
Macrophage: A leukocyte that is characterized by its ability to engulf (ingest) foreign substances such as bacteria and able to activate lymphocytes
Mast Cells: Leukocytes that have high affinity IgE receptors and are involved in triggering allergies
Natural Killer Cell: A white blood cell involved in killing unwanted cells
Neutrophil: A white blood cell that participates in host defence against bacteria and also is involved in propagating acute inflammation
Patch Test: A skin test that measures delayed reactions to an allergen
Pruritus: Itching
Rhinitis: Nasal congestion
Rhinorrhea: Clear nasal discharge
SCID: Abbreviation for Severe Combined Immune Deficiency
Skin Prick Test: Application of allergens to the skin in order to determine the presence of sensitization to an allergen
T cell: A component of the cellular part of the immune system that is involved in memory responses to foreign substances
Tryptase: An enzyme produced by mast cells that is found in acute and chronic allergic reactions. Its levels in the blood can be used to determine the presence of anaphylaxis
Urticaria: A raised rash characterized by its itchiness
Venom: Toxin present in animals such as bees and snakes that can cause an allergic reaction
Wheal: A raised bump on the skin often measured by skin prick testing for determining the presence of allergic response to an injected substance
Xerosis: Dryness of the skin of the mucus membrane
Skin Prick Test: Application of allergens to the skin in order to determine the presence of sensitization to an allergen
T cell: A component of the cellular part of the immune system that is involved in memory responses to foreign substances
Tryptase: An enzyme produced by mast cells that is found in acute and chronic allergic reactions. Its levels in the blood can be used to determine the presence of anaphylaxis
Urticaria: A raised rash characterized by its itchiness
Venom: Toxin present in animals such as bees and snakes that can cause an allergic reaction
Wheal: A raised bump on the skin often measured by skin prick testing for determining the presence of allergic response to an injected substance
Xerosis: Dryness of the skin of the mucus membrane
Complete Glossary
The Division of Allergy and Immunology provides patients and families with a complete glossary of definitions for allergic terms and diseases. Download the glossary in portable document format (pdf).
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