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Type I Hypersensitivities definitions

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  • Type I Hypersensitivity
    A rapid immune overreaction to external antigens, mediated exclusively by IgE antibodies, often resulting in allergy symptoms within 30 minutes.
  • IgE Antibody
    An immunoglobulin specialized in defending against parasites and venoms, but central to triggering allergic reactions in modern environments.
  • Allergen
    An external antigen, often harmless, that provokes immune sensitization and subsequent allergic responses upon re-exposure.
  • Mast Cell
    A tissue-resident immune cell that, when coated with IgE, releases inflammatory mediators like histamine during allergic reactions.
  • Basophil
    A circulating white blood cell that, upon IgE binding, releases granules containing substances that drive allergic symptoms.
  • Degranulation
    The process where mast cells or basophils release stored inflammatory chemicals, such as histamine, into surrounding tissues.
  • Histamine
    A potent mediator released during allergic reactions, responsible for symptoms like itching, swelling, and increased mucus production.
  • Localized Allergic Reaction
    A mild immune response confined to the site of allergen exposure, causing symptoms like rash, sneezing, or itchy eyes.
  • Systemic Anaphylaxis
    A severe, body-wide allergic reaction that can cause life-threatening drops in blood pressure and airway obstruction.
  • Anaphylactic Shock
    A critical condition marked by dangerously low blood pressure and organ failure due to widespread mediator release.
  • Prick Puncture Skin Test
    A diagnostic method where allergens are introduced under the skin to observe rapid wheal and flare reactions indicating sensitivity.
  • Immunotherapy
    A treatment involving gradual allergen exposure to retrain the immune system, aiming to reduce allergic response severity.
  • Desensitization
    A process of repeated, controlled allergen exposure intended to shift antibody production and lessen allergic reactions.
  • IgG Antibody
    A common immunoglobulin that, when produced during immunotherapy, can intercept allergens before they trigger IgE-mediated responses.
  • Hygiene Hypothesis
    A theory suggesting that reduced early-life exposure to microbes may increase susceptibility to allergic diseases.