Hypersensitivities Type I-IV Flashcards
hypersensitive
above and beyond normal response
-causes pathology
how many types of hypersensitivities?
4 types
type IV hypersensitivity
T cell mediated diseases
type I hypersensitivity
aka immediate hypersensitivity
-atopic diseases
atopic diseases
caused by Type I hypersensitivity
IgE
big player in type I hypersensitivity**
extra constant region domain
-allows it to bind Fc on mast cells
three properties controlling IgE?
1 half life of IgE
2 T cell control (need isotype switching)
3 cross-linking of IgE on surface of mast cells and basophils
half life of IgE?
2 days in serum (very short)
produced in response to allergens
half life increased when binds to mast cells and basos
receptor for IgE on mast cells and basos?
FcERI
high affinity
half-life of IgG
3 weeks woah!
receptors for IgE on B cells?
FcERII
low affinity
Th1 activation leads to?
IFN-gamma and IL-12
no upregulation of IgE
**suppressive the atopic reaction
Th2 activation leads to?
IL-4, IL-5 IL-13 leads to class switching (via IL-4) to IgE
**increases the atopic reaction
IL-5 activity?
stimulates maturation of eosinophils
allergen
antigen that gives rise to immediate hypersensitivity
-most are proteins
-usually taken in very small quantities that is sustained throughout life (ex/ dust)
food - large dose
mediators of IgE (intermediate) response in mast cells?
histamine, heparin, and tryptase (5 minutes)
also, newly generated (5-30 minutes)
- arachidonic adic
- leukotriene D4
- prostaglandin D2
**vasoactive amines and lipid mediators
late phase reaction of mast cells immediate hypersensitivty?
2-10 hours later
-cyrokines, IL-4, TNF-alpha
released by eosinophils?
cationic granule proteins and eosinophil peroxidase
**to kill worms, but can kill self cells
what must occur for mast cell activation?
binding of IgE and must be CROSS-LINKED**
allergic rhinitis?
increased mucus secretion