Download Hypersensitivity type I

Types of hypersensitivity
diseases
 The type of immune response and
immunologic mechanisms that causes
tissue injury
 The nature and location of the antigen
that is the target of this response.
Types of hypersensitivity
diseases
 Immediate H.S (Type I) caused by IgE
 Type II H.S caused by antibodies other than
IgE can cause tissue injury and interfering with
normal cellular functions.
 Type III H.S caused by deposition of circulating
Immune complexes in tissues
 Type IV or Delayed type hypersensitivity
caused by T cells and Macrophages
Disease caused by
Immune responses
*Activation of Th2 cells and production of
IgE
*Allergen
Activation of Th2
B
cell activation
IgE
binding of IgE
to Fc receptor reexposure to Allergen
release of mediators
pathologic
reactions
General features (1)
‫‪Immediate‬‬
‫‪hypersensitivity‬‬
‫‪ ‬با ورود آلرژن ‪ ،‬سلولهای ‪B‬‬
‫آن راشناسایی وپس از فعال‬
‫شدن ‪ ،‬آنتی بادی ‪ IgE‬ترشح‬
‫میکنند ‪.‬‬
General features(2)
 There is a strong genetic predisposition for the
development of immediate hypersensitivity
*high level of IgE synthesis often run in families
• Class –II MHC alleles
• One locus for atopy is on chromosome 5,near
the site of gene cluster encoding the IL-3,IL-4,
• IL-5,IL-9,IL-13 and IL-4R
‫‪General features‬‬
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‫افراد آتوپیك یا آلرژیك در مقابل عوامل آنتي ژنیك شایع‬
‫محیطي ‪،‬پروتئین هاي موجود در گرده گیاهان)‪(pollen‬‬
‫‪ ،‬مواد غذایي ‪ ،‬فضوالت حیواني‪ ،‬سم حشرات یا برخي‬
‫داروها از طریق ‪ Th2‬پاسخ میدهند‬
‫آلرژنها پروتئینهاي ریز مولكول با حاللیت باال‬
‫ایمني ذاتي را فعال نمي كنند‬
‫فراواني در محیط وبرخورد مكرر‬
‫گلیكوزیالسیون باال‬
َAllergens
 Type I is dependent on the activation of Th2
cells
 The clinical and pathologic manifestations of
Type I:increased vascular
permeability,vasodilation,smooth muscle
contraction,local inflammation
Mast cell activation
‫‪Eosinophil and Basophil‬‬
‫‪ ‬اين سلولها داراي گيرنده هاي ‪high‬‬
‫‪ affinity‬براي ‪ IgE‬بنام ‪ FCR‬مي‬
‫باشند‬
‫‪ ‬گرانولهايي سيتوپالسمي كه حاوي آنزيم‬
‫ها و ساير مدياتورهاي فارماكولوژيك‬
Mast cell activation
 Rapid release of granule
contents(degranulation)such as
Histamine,tryptase,chymase,proteoglyca
ns(heparin and chondroitin sulfate)
 Synthesis and secretion of lipid
mediators(prostaglandines ,Leukotrienes)
 Synthesis and secretion of cytokines(IL3,4,5,6,TNF-)
Mediators actions
 Histamine= bronchoconstrictor,vascular
leak,intestinal hypermotility
 PGD2=vasodilator and bronchoconstrictor ,
neut. Chemotaxis
 LTC4=bronchoconstriction,inflammation
 PAF=bronchoconstriction ,vasodilator,
inflammation
Clinical and pathologic
features
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Hay fever(allergic rhinitis)
Increased peristalsis
Bronchial asthma
Anaphylaxis
Wheal and Flare reaction
Therapy
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Inhibiting mast cell degranulation
Antagonizing the effects of mediators
Reducing inflammation
Desensitization
Anti IgE as a therapy
Drugs
 Cromolyn sodium
 Theophyllin blocks phosphodiesterase
 epinephrin
Prick test
Prick test