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
Which of the following best describes the following molecules (Leukotrienes, Prostaglandins, Thromboxanes)
A. Newly synthesized mediators
B. Pre-formed mediators
A. Newly synthesized mediators
Which cytokine/s stimulates eosinophil growth and differentiation in bone marrow?
A. IL-8
B. IL-3, IL-5, and GM-CSF
C. IL-4
B. IL-3, IL-5, and GM-CSF
Oxidation of AA by lipoxygenase results in formation of ____, as well as smooth muscle contractions, increased vascular permeability, mucus secretion
A. Leukotrienes
B. Prostaglandins
C. Thromboxanes
A. Leukotrienes
oxidation of AA by cyclooxygenase results in production of ___ and ___, which are responsible for smooth muscle tone, platelet aggregation
thromboxane, prostaglandins
Wheal and Flare reaction is a ____ type reaction whereas generalized pruritus, urticaria, or angioedema is a ___ reaction
Wheal and Flare = mild local
Pruritus = mild systemic
What are three lethal outcomes of Type 1 hypersensitivity reaction?
1) Asphyxiation - laryngeal edema
2) Suffocation - bronchiolar constriction
3) Loss of adequate BP due to peripheral edema
True or False: Wheal is edema due to increased in bv permeability while flare is due to dilation of bv
True
___ is an in vitro test for total IgE
___ is an in vitro test for specific IgE
RIST: is an in vitro test for TOTAL IgE
RAST: is an in vitro test for SPECIFIC IgE
Which drugs compete with H1 and H2 receptors and must be given prophylactically to have greatest effect?
Anti-histamines
Which drug stabilizes mast cell membranes?
Which drug prevents arachidonic acid pathways?
Cromolyn sodium - stabilizes mast cell membrane
Corticosteroids - prevent AA pathway
Which drug reverses effects of histamine?
Epinephrine
___ is a leukotriene receptor antagonist while __ is a humanized anti-IgE antibody
Montelukast
Omalizumab
_____: injection of allergen with very dilute dose of antigen; done over span of weeks to months
Allergen Immunotherapy
How is immunotherapy different from desensitization?
In allergen immunotherapy: injection of allergen is increased over span of WEEKS or MONTHS
In desensitization: larger doses of drug is given of period of HOURS
