1. 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.

2. 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

3. Disease caused by Immune responses
*Activation of Th2 cells and production of IgE
*Allergen Activation of Th B cell activation IgE binding of IgE to Fc receptor reexposure to Allergen
release of mediators pathologic reactions

4. General features (1)

5. Immediate hypersensitivity
با ورود آلرژن ، سلولهای B آن راشناسایی وپس از فعال شدن ، آنتی بادی IgE ترشح میکنند .

6. 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

7. General features
افراد آتوپيك يا آلرژيك در مقابل عوامل آنتي ژنيك شايع محيطي ،پروتئين هاي موجود در گرده گياهان(pollen) ، مواد غذايي ، فضولات حيواني، سم حشرات يا برخي داروها از طريق Th2 پاسخ ميدهند
آلرژنها پروتئينهاي ريز مولكول با حلاليت بالا
ايمني ذاتي را فعال نمي كنند
فراواني در محيط وبرخورد مكرر
گليكوزيلاسيون بالا

8. َ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

9. Mast cell activation

10. Eosinophil and Basophil
اين سلولها داراي گيرنده هاي high affinity براي IgE بنام FCR مي باشند
گرانولهايي سيتوپلاسمي كه حاوي آنزيم ها و ساير مدياتورهاي فارماكولوژيك

11. Mast cell activation
Rapid release of granule contents(degranulation)such as Histamine,tryptase,chymase,proteoglycans(heparin and chondroitin sulfate)
Synthesis and secretion of lipid mediators(prostaglandines ,Leukotrienes)
Synthesis and secretion of cytokines(IL-3,4,5,6,TNF-)

12. Mediators actions
Histamine= bronchoconstrictor,vascular leak,intestinal hypermotility
PGD2=vasodilator and bronchoconstrictor , neut. Chemotaxis
LTC4=bronchoconstriction,inflammation
PAF=bronchoconstriction ,vasodilator,
inflammation

13. ‍‍Clinical and pathologic features
Hay fever(allergic rhinitis)
Increased peristalsis
Bronchial asthma
Anaphylaxis

14. Wheal and Flare reaction

15. Therapy Inhibiting mast cell degranulation
Antagonizing the effects of mediators
Reducing inflammation
Desensitization

16. Anti IgE as a therapy

17. Drugs
Cromolyn sodium
Theophyllin blocks phosphodiesterase
epinephrin

18. Prick test

19. Prick test