28 Questions
What initiates IgE-mediated degranulation?
Antigen cross-linkage
What is necessary for the movement of granules to the plasma membrane during degranulation?
A+C
Which drug is used to block the Ca++ influx as a treatment for allergies?
Disodium cromoglycate
What is the initial event that triggers IgE-mediated degranulation?
Cross-linkage of allergen-bound IgE with the Fc receptor on mast cells or basophils
What is the role of Ca++ influx in mast cell degranulation?
Promoting the assembly of microtubules and contraction of microfilaments
What is the result of IgE cross-linkage?
Mast cell degranulation
Which intracellular signaling process is involved in initiating mast cell degranulation?
A+C
Which process is rearranged during mast cell degranulation?
Cytoskeleton
What are the most significant primary mediators of Type I hypersensitivity?
Histamine, proteases, eosinophil chemotactic factor, heparin
Which agents are produced before degranulation and stored in the granules?
Proteases and histamine
When do the primary mediators of Type I hypersensitivity occur?
2-3 minutes to 6 hours
What type of agents are synthesized after target-cell activation or released during the degranulation process?
All of the above
What is the timing difference between the formation of leukotrienes and prostaglandins compared to histamine?
Leukotrienes and prostaglandins form after mast cell degranulation, while histamine forms before degranulation
Which biological effects of leukotrienes and prostaglandins are more pronounced and longer lasting than those of histamine?
Bronchoconstriction, vascular permeability, mucus production
Which cytokines are secreted by human mast cells to alter the local microenvironment and recruit inflammatory cells?
IL-4, IL-5, IL-6, TNF-α
How does systemic anaphylaxis typically start?
With sudden skin redness and intense itching and hives
What is the usual initiation point of systemic anaphylaxis?
Direct entry of allergen into the bloodstream
Which of the following symptoms is associated with anaphylactic shock?
A+B
What can cause the patient to die of suffocation in systemic anaphylaxis?
Contraction of smooth muscles due to allergen inhalation
What is the common name for Allergic Rhinitis?
Hay fever
Where does the reaction develop in allergic asthma (extrinsic asthma)?
Lower respiratory tract
What is the characteristic symptom of Allergic Rhinitis (hay fever)?
Watery exudation of conjunctivae
Immunotherapy involves Desensitization: subcutaneous injections of allergens to cause a shift to IgG production instead of IgE.
True
How can antibody-bound cells be destroyed in Type II hypersensitivity reactions?
By activating the complement system and creating pores in the cell membrane
What is the mechanism of cell destruction in antibody-dependent cell-mediated cytotoxicity (ADCC)?
Cytotoxic cells bind to the Fc region of antibodies and promote killing of the cells
What role does opsonization play in Type II hypersensitivity reactions?
Enabling phagocytic cells to bind and phagocytose the antibody-coated cell
RBCs have different antigen ,but the most important are A and B antigens(used for blood grouping ABO).
True
Antibodies to the A, B, and O antigens, called isohemagglutinins, are usually of the IgM class
True
Test your knowledge on the process of IgE-mediated degranulation, which is initiated by cross-linkage of IgE with an allergen, leading to mast cell degranulation through intracellular signaling and calcium influx.
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