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31 Cards in this Set
- Front
- Back
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Type I hypersensitivity is involved in what type of disease?
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- allergic
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What are the immunological mechanisms involved in allergic disease?
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- sensitized by allergen
- penetrates mucosa and comes in contact with APC - APC displays peptide MHC type II - Th2 cell interacts with APC - Th2 interacts with B cell - B cell produces IgE for Ag - mast cell is sensitized for specific Ag - after 2nd + exposure to Ag, mst releases mediators |
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Where is IgE - forming cells mainly located?
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- bronchial, peritoneal
- respiratory mucosa - GI mucosa |
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What is the IgE concentration in the serum?
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- .0001
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Can IgE pass through th eplacenta?
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- no
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Does IgE have skin sensitization properties?
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- yes
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What are 4 characteristics of Reagin/IgE
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1) present in atopic sera
2) sensitize homologous tissue 3) Heat ----sensitive: Fc part of IgE ----stable: Fab part IgE 4) Mercaptoethanol sensitive |
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What signals/molecules are required for B cell to produce IgE?
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Signal 1: IL4/13 from Mast/Th2/Basophil
Signal 2: CD40/CD40L binding with T cell |
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What is the immediate effect of an Ag binding to the IgE on a mast cell?
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- granule exocytosis
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What molecules do granules contain and what do they do?
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- vasoactive amines: vascular dilation and smooth muscle contraction
- proteases: tx damage |
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What are 2 later consequences of Allergen binding to IgE on mast cell?
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1) Enzymatic modification of arachidonic acid
2) Transcriptional activation of cytokines |
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What occurs with enzymatic modification of arachidonic acid?
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- produces lipid mediators which go into 2 pathways
1) prostaglandins: vascular dilation 2) leukotrienes: smooth muscle contraction |
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What does the mast cell activation of cytokine genes cause?
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- inflammation
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Activated mast cells/basophila secretes? which do?
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1) biogenic amines, lipid mediators (vascular permeability, bronchoconstriction, intestinal hypermotility)
2) cytokines/lipid mediators (inflammation) 3) enzymes (tx damage) |
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Eosinophils release what when encountering IgE? which do?
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- granule proteins (kill parasites and host cells)
- enzymes (tx damage) |
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If activated macrophage releases high amounts of IL-12 is Th1/Th2 activated?
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- Th1
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Low-dose of Ag induces Th1/Th2?
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- Th2
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What does Th2 release and what does this cause in hypersensitivity?
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- IL4/13: IgE expression
- IL5: eosinophil activation |
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If a normal allergic Ag encounters a T cell, will it induce Th1/Th2?
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- Th1
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If an atopic allergic Ag encounters a T cell, will it induce Th1/Th2?
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- Th2
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Does Th1 or Th2 orchestrate the allergic response?
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- Th2
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What role does Th1 have in allergic response?
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- aggregating/decreasing Th2 response
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What factors induce the release of mediators from mast cell after the allergen binds?
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- hypoxia
- drugs - histamine releasing factors - different cells: neutro, eosin, et - ca Ionophore - Anaphylatoxins - Physical stimuli - Neurohromones |
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What is Rast?
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- an in vitro test for people with skin problems so you cannot do a normal skin allergen test
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Describe the steps of Rast
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- paper disc with Ag + serum
- Ab bind - Add I-anti-IgE - wash and count |
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What is direct organ challenge?
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- patient inhales Ag
- pulmonary function test (FEV-1) - Immediate response b/c release histamine/leuotrienes - late response due to cytokiens/inflammation |
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Describe the pathway of IgE and parasitic infections
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1) Soluble Ag goes through gut mucosa lining into lymph node
2) APC processes Ag 3) T cell displays to B 4) histamines are produced 5) extravasation occurs 6) IgE crosses back through mucosa to worm |
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What does CpG do?
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- Enhances T-Bet to produce TH1
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What is the correlation btw IgE levels and asthma?
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- patients with increasing amounts of IgE are more likely to have asthma
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What are characteristics of Omalizumab/Xolair?
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- humanized mouseAb against IgE
- binds circulating IgE no matter the specificity - Forms complexes of Omalizumab and IgE - does not activate complement |
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How does Omalizumab work?
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- binds to the FceRI binding site on the IgE molecule
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