Questions and Answers
What type of antibody is primarily involved in the reaction described?
What is one of the immediate effects of histamine release?
What response occurs upon re-exposure to the same antigen?
Which symptom is typically associated with the immediate phase of the allergic reaction?
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What does the cross-linking of IgE antibodies on mast cells lead to?
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What is an allergen defined as?
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Through which mechanism might allergens lead to cytotoxic reactions?
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What type of reactions are associated with Type II hypersensitivity?
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Which of the following correctly describes the entry of allergens into the body?
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What is the role of specific IgE in allergic reactions?
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Study Notes
Allergens and Immune Response
- Allergens are antigens causing the production of specific IgE antibodies.
- Entry routes for allergens can include direct inhalation, ingestion, or skin contact.
- Type II hypersensitivity involves cytotoxic reactions that trigger allergy symptoms and may involve infections or self-antigens.
Immediate Reaction Phase
- IgE antibodies are formed in response to the allergen and bind to mast cells via their Fc portion.
- Upon re-exposure to the same allergen, cross-linking of IgE on mast cells occurs, leading to degranulation.
- This degranulation releases histamine, a key mediator in allergic responses.
- Histamine's effects include:
- Blood vessel dilation and increased permeability (causing swelling and redness).
- Increased mucus secretion (resulting in a runny nose).
- Smooth muscle contraction in bronchi, which may lead to breathing difficulties.
Type III Hypersensitivity Reactions
- Involves immune complex formation, either locally or in circulation.
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Clinical Types:
- Systemic immune complex diseases like Systemic Lupus Erythematosus (SLE), where autoantibodies target DNA.
- Certain infections (e.g., Hepatitis B, HIV) can prompt immune complex responses.
- Post-streptococcal glomerulonephritis involves deposition of streptococci-antibody complexes in kidneys, a common cause of renal failure.
Local Immune Complex Diseases
- Arthus reaction represents a local immune complex reaction often triggered by unusual or large amounts of antigen-antibody complexes.
- Diagnosis may involve detection of specific antibodies in patient serum.
Clinical Associations
- Many SLE patients also exhibit symptoms of Sjögren syndrome, which includes reduced saliva leading to dental problems and oral mucosal ulcers.
- Oral aphthae are characterized by cycles of painful lesions in the lips, buccal mucosa, soft palate, and tongue, with an emphasis on exclusion of other clinical causes.
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Description
Test your knowledge on the role of allergens in triggering immune responses, including the formation of IgE antibodies and the associated hypersensitivity reactions. Explore the immediate reaction phase and the impact of histamine on the body's systems. This quiz covers essential concepts in immunology and allergies.
