Exam 10: Chapter 14 (Allergies) Flashcards
What are the properties of eosinophils?
- Present in the connective tissue underlying the epithelium
- Activated by external signals to release their granules
- Synthesize and secrete cytokines and lipid mediators after releasing their granules
What does the production of IgE rely on?
TH2 cells, which make IL-4, the substance that promotes class switching to IgE
What are the properties of allergens?
- Have to activate TH2 responses (must be proteins)
- Must be small enough to spread through air
- Must be stable and soluble
- Many are proteases
What are the immune system reactants for Type IV hypersensitivity?
TH1 cells, TH2 cells, and CTL
What can Type III hypersensitivity inflammation lead to?
Clotting and hemorrhage of the skin
Why is it important that mast cell activation is localized?
Effects of degranulation and secretion of inflammatory modulators on other tissues is minimized
What happens if allergic asthma progresses to chronic asthma?
Specific allergens are no longer necessary to activate an asthma response
What is another term for Type IV hypersensitivity?
Delayed type hypersensitivity
What is required for the production of mast cells?
Cytokine Stem Cell Factor (SCF)
Why do multiple antigens have the ability to activate the same mast cell?
Mast cells contain IgE specific for a number of different antigens, any of which can activate the mast cell
What is angioedema?
Diffuse swelling due to the activation of mast cells in the deeper layers of skin
How do basophils function?
Once activated by IgE, they release inflammatory mediators similar to mast cells
What causes Type IV hypersensitivity?
Antigen specific effector T cells
What is the consequence of activating the parasite response in the case of allergies?
Damage to normal tissues
What sort of reactions are caused by food allergens?
Smooth muscle contractions in the gut, urticaria and angioedema due to absorption of allergen into the blood
What is the role of TNF-alpha?
To work in concert with histamine to promote inflammation
What are the two roles of histamine?
- To act on endothelial cells to increase vascular permeability
- To act on smooth muscle cells, causing them to contract
How are basophil and eosinophil production related?
They are inversely proportional (increased production of one decreases production of the other)
What is required in order to elicit a Type I hypersensitivity response?
Prior exposure to the antigen that induces an IgE response
What must occur in order to get activation of the signaling pathway in Type I hypersensitivity?
Cross-linking of the FCeRI receptors for IgE
What immunoglobulin class mediates Type II hypersensitivity responses?
IgG
What is atopy?
A genetic predisposition to allergies
What is the late phase reaction?
Reaction that occurs hours after the immediate reaction and can last for hours. Caused by production of cytokines, leukotrienes, and chemokines by activated mast cells