Hypersensitivity

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Hypersensitivity
Classification Gell Coombs Type I
Anaphylactic or Immediate Type II
Cytotoxic or Cytolytic Type III Arthus
or Immune complex Type IV Delayed
hypersensitivity
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I. Anaphylactic Hypersensitivity
( Atopy, Allergy ) Antigen ( Allergen ) -
protein - polypeptide - polysaccharide -
nucleic acid - low M.W chemicals
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Common Allergens - House dust mite -
Pollen - Animal dander - Microorganisms -
Serum protein/Animal protein - Antibiotic (
penicillin, streptomycin ) - Insect poison
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Charecteristic of Allergen 1. Low
M.W lt 40 kD 2. Water soluble 3.
Stability
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Route of Allergen Entry - Skin -
Respiratory tract - GI tract - Eye
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Mechanism of type I Hypersensitivity Ag
Body B-cell IgE-
Ab Chemical mediators Mast cell
- Histamine Ag - Serotonin
- etc.
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Chemical mediators - Histamine -
Serotonin - kinin - Slow reactive
substance of anaphylaxis ( SRS-A )(
Leukotrienes ) - Platelet activating factor (
PAF ) - Eosinophil chemotactic factor of
anaphylaxis ( ECF-A )
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• Chemical Mediator Release
• Early phase 2-3 min. to 6 hr.
• - histamine
• - eosinophil chemotactic facter ( ECF )
• - neutrophil chemotactic factor ( NCF )
  etc.
• Late phase gt 6 hr. - 24 hr.
• - SRS-A ( Leukotrienes )
• - PAF ( platelet activating factor )
• - vasoactive amine

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• Physiological Effect of Mast Cell Mediator
• Chemo-attractants
• Neutrophil chemotactic factor(NCF)
  Neutrophil
• -Eosinophil chemotactic factor(ECF)
  Eosinophil
• -Leukotrienes(LTB4) Monocyte/Basophil
• Activators
• -Histamine Vasodilatation Vascular
  permeability
• -PAF Thrombi -Tryptase Activate C3
• -Kininogenase Kinin Vascular
  dilatation

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Spasmogens - Histamine
- Bronchial smooth - Prostaglandin
muscle contraction -
Leukotriene-C4
-Mucosal edema - Leukotriene-D4
- Mucus secretion
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Target Organs Smooth muscle
Contraction Capillary
Dilatation Mucous gland Increase
secretion
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Example of diseases - Bronchial asthma -
Allergic rhinitis - Urticaria - Anaphylactic
shock - Food allergy - Eczema - Hay fever
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Risk of Allergy Parents both 50
one 30 none 15 ( 30
)
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Laboratory Testing 1. Skin test ( Prick test
) 2. Prausnitz-Kustner ( PK ) test Allergenic
serum Normal skin ( human )

allergen
Wheal Flare
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3. Passive cutaneous anaphylaxis ( PCA )
test Allergic i.d Normal skin
(G.P) serum
i.v allergen 24 h.
Evan blue
Blue skin 4. Histamine
determination 5. IgE lavel - RIA 6. Eosinophil
count 10-20
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• Treatment Prevention
• 1.Allergen avoidance
• - Environmental control
• 2. IgE removement
• 2.1 Hyposensitization ( Desensitization )
• Allergen i.d Blocking IgG

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2.2 Remove IgE out of serum Blood
Plasmapheresis Plasma Body
Rbc Affinity

chromtography Plasma without IgE
(Anti-IgE)
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3. Inhibition of mediators release 3.1
Methylxanthines theophylline
theophylline
cAMP 5 AMP 3.2 ß-Adrenergic
receptor stimulators epinephrine
ß -adrenergic receptor
cAMP ATP adenyl cyclase

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4. Histamine antagonist (Anti-histamine)
Histamine Target
Anti-histamine
cell - sodium cromoglycate( cromolyn
) 5. Late phase inhibitor
steroid, indomethacin
SRS-A Target cell steroid
anti-inflammation