Hypersensitivity Flashcards
Which type is the immediate type?
Type I
Which type is modified self?
Type II
Which type is due to immune complex disease?
Type III
Which type is delayed type?
Type IV
Which type is IgE mediated?
Type I
Which type is IgG mediated?
Type II and III
Which type is T cell mediated?
Type IV
What is the effector mechanism of Type I?
Mast cell activation
What is the effector mechanism of Type II?
If cell/matrix associated Ag: complement and cells containing Fc receptors (phagocytes and NK cells)
If cell surface receptor bond to Ag:Ab alter signaling
What is the effector mechanism of Type III?
Complement and Phagocytes
What is the effector mechanism of Type IV?
Th1 cells activate macrophages, Th2 cells activated eosinophils, or CTLs induce apoptosis
What are some examples of Type I?
Allergic rhinitis, asthma, systemic anaphylaxis
What are some examples of Type II w/ cell or matrix associated Ag?
Durg allergies, namely penicillin
What are some common sources of allergens?
- Inhaled:plant pollens, pet dander, mold spores, feces of very small animals (dust mites)
- Injected: insect venoms, vaccines, drugs, therapeutic proteins
- Ingested: food, orally administered drugs
- Contacted: plant leaves, industrial products made from plants, synthetic chemicals in industrial products, metals
What are some examples of Type II w/ cell surface receptor bound to Ag?
chronic urticaria
What are some examples of Type III?
serum sickness, arthus rxn
What are some examples of Th1 mediated Type IV?
contact dermatitis, tuberculin rxn
What are some examples of Th2 mediated type IV?
chronic asthma, chronic allergic rhinitis
What are some examples of CTL mediated Type IV?
contact dermatitis
Will a hypersensitivity rxn occur upon first encounter w/ Ag?
No, the first exposure will prime the allergic response. The hypersensitivity rxn will not take place until second exposure
Can Th1 cells lead B cells to release IgE?
No
How long does it take for a Type I to occur?
minutes
What type of inhaled Ag promotes the priming of Th2 cells to drive an IgE response?
protein Ag b/c only they can induce T cell responses
What type of function do those Ag’s have? refer to an Ag that is required to prime a Th2 cell to drive an IgE response
These allergens are often proteases
T or F. High doses of inhaled Ag promotes the priming of Th2 cells to drive and IgE response. (refer to an Ag that is required to prime a Th2 cell to drive an IgE response)
F. Low doses favor activation of Il-4 producing CD4 T cells
Do inhaled allergens have a high or low molecular weight? (refer to an Ag that is required to prime a Th2 cell to drive an IgE response)?
low molecular weight so they can diffuse out of particle and into mucus
Do inhaled allergens have a high of low solubility (refer to an Ag that is required to prime a Th2 cell to drive an IgE response)?
high solubility that is readily eluted from particle
Are inhaled allergens highly stable (refer to an Ag that is required to prime a Th2 cell to drive an IgE response)?
yes so they can survive in a desiccated particle
Do inhaled allergens contain peptides that bind to host MHC class II molecules (refer to an Ag that is required to prime a Th2 cell to drive an IgE response)?
yes, this is required for T cell priming
What causes mast cell degranulation?
cross linking of IgE bound on mast cell surface w/ Ag
What enzymes do mast cells release?
tryptase, chymase, cathepsin G, carboxypeptidase
What toxic mediators do mast cells release?
histamine and heparin
What cytokines do mast cells release?
TNF-alpha, IL4, IL3, IL13, Il5, GM-CSF
Which chemokine do mast cells release?
CCL3
What lipid mediators do mast cells release?
Leukotrienes C/D/E4s and PAF
What is the role of histamine (and heparin)?
toxic to parasites, increases vascular permeability, and causes smooth muscle contraction
What is the role of the enzymes released by mast cells?
to remodel the connective tissue matrix