Lecture 14: Type 1 Hypersensitivity Reactions Flashcards
Which antibody mediates Type 1 hypersensitivity reactions?
A. IgD
B. IgE
C. IgM
B. IgE
Which hypersensitivity reaction is antibody mediated? immune complex mediated?
antibody mediated = type 2
immune complex mediated = type 3
Which hypersensitivity reaction is T cell mediated?
Type 4
True or False: Complement activation/recruitment and activation of leukocytes, as well as IgM and IgG antibodies are involved in both Type II and Type III hypersensitivity reactions
True
What mechanism of tissue disease and injury is used by Type IV hypersensitivity reactions?
- Direct target cell lysis
- Cytokines
- Activate macrophages
Transfusion reactions and hemolytic disease of newborn are associated with:
A. Type 1 Hypersensitivity
B. Type 2 Hypersensitivity
C. Type 3 Hypersensitivity
D. Type 4 Hypersensitivity
B. Type 2 Hypersensitivity
Arthus reactions and serum sickness are associated with:
A. Type 1 Hypersensitivity
B. Type 2 Hypersensitivity
C. Type 3 Hypersensitivity
D. Type 4 Hypersensitivity
C. Type 3 Hypersensitivity
DHT and Contact Derm are associated with:
A. Type 1 Hypersensitivity
B. Type 2 Hypersensitivity
C. Type 3 Hypersensitivity
D. Type 4 Hypersensitivity
D. Type 4 Hypersensitivity
Mast cells, basophils, and their products (histamines, vasoactive amines, AA metabolites) are the mechanism of tissue injury and disease for which hypersensitivity reaction?
A. Type 1 Hypersensitivity
B. Type 2 Hypersensitivity
C. Type 3 Hypersensitivity
D. Type 4 Hypersensitivity
A. Type 1 Hypersensitivity
True or False: Allergies, Asthma, and Anaphylaxis are mediated by IgE
True
8 steps of type 1 hypersensitivity?
SENSITIZATION
1) exposure to allergen
2) IgE production
3) binding of IgE to surface receptors on mast/basophils
ACTIVATION
4) re-exposure
5) binding of allergen to cell-associated IgE
6) signal transduction in mast/basophil
7) mediator release
8) mediator effects on end organs
Primary exposure of an antigen to the ___/____ tract and the skin tend to induce more IgE production
respiratory and GI tract
note: mast cells and IgE bearing B cells tend to line the skin, mucous membranes, and connective tissues of these areas
IgE production is ___ dependent
Th2
-meaning, with assistance from Th2 cells, B cells differentiate into IgE secreting plasma cells
Which Th2 cytokines can enhance IgE responses?
IL-4 and IL-5
What is the name of the high affinity receptor that IgE binds to on mast cells or basophils?
How is this beneficial?
Fc epsilon RI
- Binding extends the half life of IgE
Which cells are the main effectors of Type 1 hypersensitivity reactions?
Mast cells
What is the most important feature of mast cells and basophils?
They possess FC-epsilon-RI
Which corresponds to the Activation Phase:
A. First exposure
B. Second Exposure
B. Second Exposure
True or False: Memory cells are involved in the activation phase
True
During activation phase, allergen binds to at least 2 ___ molecules on mast cells, resulting in ___
IgE; cross-linking molecules (bringing FcERI together)
“receptor aggregation”
True or False: release of pharmacologically active mediators causes inflammation through capillary dilation and increased blood vessel permeability
True
True or False: Degranulation means cell death will occur
False
(cell can, and often does, survive to regenerate its granules)
What are the four pre-formed mediators (immediate release and effects)?
-Histamine
-Serotonin
-ECF-A/protease/hydrolase
-Heparin
What effects do both histamine and serotonin share?
Increased vascular permeability, pruritus, increased exocrine secretions
