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Questions and Answers
What was the outcome for the dogs after receiving the second injection of the toxin?
What characterizes immediate hypersensitivity reactions?
What term did Richet use to describe the overreaction of the immune system observed in the dogs?
How do delayed-type hypersensitivity (DTH) reactions differ from immediate hypersensitivity reactions?
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Which immunologists proposed a classification scheme for differentiating types of hypersensitivity reactions?
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What is one of the immediate effects of mast cell activation?
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Which type of mediator is released by activated mast cells for long-term effects?
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Which of the following is NOT a function of mast cell mediators in inflammation?
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Over what time frame do acute changes associated with mast cell activity typically occur?
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What is the primary role of leukotrienes among mast cell mediators?
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Which cells are considered cellular targets of mast cell mediators?
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What can be an effect of long-term mast cell mediator production?
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Which type of cell is primarily involved in tissue remodeling due to mast cell activation?
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What type of cell does IgE bind to during an immediate type I hypersensitivity reaction?
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Which of the following substances is released from sensitized mast cells during degranulation?
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In the context of type I hypersensitivity, what role do TH2 cells play?
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What is a key characteristic of the immediate type I hypersensitivity reaction?
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Which component is crucial for the binding of allergen-specific IgE?
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Which cells are primarily involved in the local inflammatory response during an immediate hypersensitivity reaction?
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What effect does the release of vasoactive amines have during an immediate hypersensitivity reaction?
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Which type of immune cell develops into plasma cells after activation by TH2 cells?
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Which cytokine is specifically important for the recruitment and activation of eosinophils?
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What clinical manifestation can result from a type I hypersensitivity reaction?
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What role does IL-8 play in the hypersensitivity response?
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Which cytokines stimulate the TH2 response and increase IgE production by B cells?
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What effect does histamine binding to H2 receptors on mast cells have?
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Which cytokine contributes to shock in systemic anaphylaxis due to its high secretion by mast cells?
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How do GM-CSF and other cytokines influence myeloid cells?
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Which of the following is NOT a localized reaction associated with type I hypersensitivity?
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What is the primary goal of hyposensitization in allergy treatment?
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Which immune response is primarily associated with hyposensitization therapy?
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Which additional cells are involved in the hyposensitization process that enhances tolerance?
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What is the typical positive control used in skin tests for hypersensitivity reactions?
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Which type of response is co-clustering of antigen with inhibitory Fc receptors associated with?
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What happens to IgG4 levels during successful hyposensitization therapy?
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Which condition is used as a negative control in skin testing for hypersensitivity?
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What role do TGF-β and IL-10 play in the context of hyposensitization?
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Study Notes
Anaphylaxis and Hypersensitivity Reactions
- Anaphylaxis is an overreaction of the immune system resulting in severe and immediate symptoms like vomiting, diarrhea, asphyxia, and death.
- It was first described by scientist Paul Portier and Charles Richet, who experimented with jellyfish toxins on dogs.
- The term "anaphylaxis" comes from the Greek words "ana" (against) and "phylaxis" (protection) and refers to a reaction that overprotects the body.
- Anaphylaxis is an example of a Type I hypersensitivity reaction, a category defined by P.G.H. Gell and R.R.A. Coombs.
Type I Hypersensitivity Reaction Key Facts
- Primarily involve antibody-antigen interactions, specifically IgE antibodies, which bind to mast cells and basophils.
- Upon contact with allergens, these cells release inflammatory mediators like histamine, proteases, and heparin.
- These mediators act on various cells and tissues, causing immediate changes like inflammation and altered blood vessel permeability.
Other Type I Hypersensitivity Reactions
- Include symptoms like hay fever, eczema, and asthma, which are less severe than anaphylaxis.
- Desensitization therapy can help manage type I hypersensitivity by suppressing the formation of IgE antibodies.
- Hyposensitization works by gradually introducing small doses of allergens to induce the production of IgG antibodies, which compete with IgE for binding to allergens.
Mast Cells: Key Players in Type I Reactions
- Mast cells are important immune cells involved in type I hypersensitivity reactions. They reside in tissues and release a variety of inflammatory mediators.
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Mediators secreted by mast cells have a range of effects:
- Histamine acts on H1 receptors causing increased vascular permeability and vasodilation.
- Proteases degrade proteins and contribute to tissue breakdown.
- Heparin acts as an anticoagulant.
- Mast cells also produce interleukins, which are cytokines that influence other immune cells like neutrophils, eosinophils, and T cells.
The Role of T cells in Type I Hypersensitivity
- T cells can influence type I hypersensitivity reactions, specifically through the induction of T helper 2 (TH2) cells, which stimulate IgE production by B cells.
- IL-4, IL-5, and IL-13 are cytokines secreted by mast cells and basophils and play significant roles in TH2 cell differentiation and IgE production.
Chronic Inflammation in Type I Hypersensitivity
- Chronic type I hypersensitivity can contribute to tissue remodeling, leading to long-term changes in tissues.
- The release of inflammatory mediators from mast cells and other cells can stimulate fibroblast proliferation, collagen deposition, and new blood vessel formation.
Preventing Type I Reactions
- Hyposensitization therapy involves repeated injections of allergens in increasing doses to increase IgG antibodies and reduce IgE production.
- This can lead to tolerance, a reduced immune response to the allergen.
- Immunotherapy is another term for hyposensitization.
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Description
Explore the complex world of anaphylaxis and hypersensitivity reactions in this quiz. Learn about the immune system's overreactions, the role of IgE antibodies, and the historical context behind these vital concepts. Test your knowledge of the key facts and mechanisms involved.
