Week 3 Type 1 Hypersensitivity Reaction Flashcards
(26 cards)
What is a Type I hypersensitivity reaction?
An abnormal immune response triggered by exposure to specific antigens known as allergens.
What initiates the cascade of immunologic events in Type I hypersensitivity?
The presentation of the antigen to the T-helper cells (Th cells).
What type of antibodies are produced in a Type I hypersensitivity reaction?
Antigen-specific IgE antibodies.
What symptoms are caused by the degranulation of IgE-bound mast cells and basophils?
Various allergy symptoms, which can be local or systemic.
What severe reaction may occur in Type I hypersensitivity?
Anaphylactic shock.
What tests are available to determine allergic etiology?
Skin testing and in vitro tests.
What are common treatment options for Type I hypersensitivity?
Antihistamines and glucocorticoids.
True or False: Anaphylaxis requires immediate airway access and administration of epinephrine.
True.
What is the lifetime prevalence of allergies worldwide?
15%.
In the United States, what rank do allergies hold as a cause of chronic illness?
6th-leading cause.
Name two factors contributing to the increased prevalence of allergic diseases.
- Improved hygiene * Increased pollution.
What is the sensitization stage in the pathophysiology of Type I hypersensitivity?
Asymptomatic first antigen exposure where the allergen is recognized by antigen-presenting cells.
What do Th2 cells release during the sensitization stage?
Interleukins (IL-4, IL-5, IL-13).
What occurs during the early-phase reaction of Type I hypersensitivity?
Degranulation of IgE-bound mast cells and basophils, releasing mediators.
List some mediators released during mast cell degranulation.
- Histamine * Prostaglandin * Platelet-activating factor * Leukotrienes.
What characterizes the late-phase reaction in Type I hypersensitivity?
Eosinophils and other leukocytes migrate to allergen-contaminated tissue, occurring 4–12 hours later.
Fill in the blank: The most common causes of Type I hypersensitivity include drugs, food, insect venom, and _______.
Environmental allergens.
What is anaphylaxis?
A severe, life-threatening systemic hypersensitivity reaction occurring within minutes of allergen exposure.
What is the immediate treatment for anaphylaxis?
Administration of epinephrine.
What are the advantages of skin testing for allergies?
- Results available within 15–20 minutes * Less costly * Patients can see their reactions.
What is a disadvantage of in vitro testing for allergies?
It is expensive.
What therapeutic options are available for localized allergic reactions?
- H1 blockers/antihistamines * Inhaled bronchodilators * Intranasal glucocorticoids * Oral glucocorticoids.
What is the role of anti-IgE immunotherapy in managing allergies?
It is used for severe asthma.
What should patients with a history of anaphylaxis wear?
A MedicAlert bracelet.
