This is the simple way to summerize whole allergic reaction in immunology

1. Hypersensitivity
By:
A. M. Makandar
Assistant professor
Vivekanand college.

2. Contents:
 Introduction
 Four types of Hypersensitivity
 Mechanism
 Prevention
 Importance

3. Defination of Hypersensitivity
 It can be defined as the harmful aspect
of immunity , the injurious effects
developed in a sensitised host after
administration of same antigen which
results in to tissue damage.disease or
death is called Hypersensitivity.
 Gell and Coombs classified
Hypersensitivity reaction in to 4 types
based on actual mechanism of reaction.

4. IgE-Mediated (Type I)
Hypersensitivity

5. Common allergens

6. Mast cell degranulation

8. Intracellular events of Mast cell
degranulation

9. Kinetics of major bio-chemical
events

10. Principle mediators in type-1
Hypersensitivity
Primary Mediators
 Histamine, heparin-Increased vascular
permeability; smooth-muscle contraction
 Serotonin-Increased vascular permeability;
smooth-muscle contraction
 Eosinophil chemotactic factor (ECF-A)-Eosinophil
chemotaxis
 Neutrophil chemotactic factor (NCF-A)- Neutrophil
chemotaxis
 Proteases-Bronchial mucus secretion; degradation
of blood-vessel basement membrane;generation of
complement split products

11. Secondary Mediators
 Platelet-activating factor-Platelet aggregation and
degranulation; contraction of pulmonary smooth
muscles
 Leukotrienes (slow reactive substance of
anaphylaxis, SRS-A)-Increased vascular
permeability; contraction of pulmonary smooth
muscles
 Prostaglandins-Vasodilation; contraction of
pulmonary smooth muscles; platelet aggregation
 Bradykinin-Increased vascular permeability; smooth-
muscle contraction
 Cytokines
IL-1 and TNF- α:Systemic anaphylaxis; increased
expression of CAMs on venular endothelial cells
IL-2, IL-3, IL-4, IL-5, IL-6, TGF-, and GM-CSF Various
effects

12. The early and late inflammatory
responses in asthma
Early Response(minutes)
Histamine Vasodilation
PGD2 Bronchoconstriction
LTC1 Mucus secretion
Late Response(hours)
IL-4,TNF-α,LTC-4 Increased endothelial cell
adhesion
PAF,IL-5,ECF Leukocyte migration
IL-4,IL-5 Leukocyte activation

14. Effect of IL-4 and IFN- on in vitro
production of IgE

15. RIST

16. RAST

17. Hyposensitization

18. Drugs used to treat type-I
hypersensitivity

19. Antibody-Mediated Cytotoxic
(Type II)-Hypersensitivity
Ab directed against cell surface antigens meditates
cell destruction via complement activation or
ADCC

21. Type-III/Immune Complex Reactions

22. Development of symptoms of
serum sickness

23. Type-IV/Delayed-Type
Hypersensitivity (DTH)

25. Formation of a granuloma

26. Role of IFN- in host defense against
intracellular pathogens

27. Development of DTH reaction
after a second exposure to poison oak

29. Questions