1. kidney

2. kidney

3. Allergy and Hypersensitivity
Dr Farzana Salman

4. Allergy and Hypersensitivity
Hypersensitivity is the term used when an immune response results in exaggerated or inappropriate reactions harmful to the host.
Allergy is often equated with hypersensitivity but should be limited to the IgE mediate reactions.

5. Classification Antibody mediated hypersensitivity Type I ------- IgE
Type II IgG
Type III IgG
Cell mediated hypersensitivity
Type IV----- T lymphocytes

6. Classification Immediate hypersensitivity----- B Lymphocytes
Delayed hypersensitivity T Lymphocytes

7. Type I---Atopic Allergy

8. Antigen induces the formation of IgE antibody (Reagins or sensitized antibodies)
Binds firmly to the surface of mast cells and basophils.
Reexposure to the same antigen results in cross linking to the cell bound IgE antibody.
Degrannulation
Release of pharmacologically active mediators within minutes. ( Calcium mediated release)

9. Histamine
Protease
Slow reacting substance of anaphylaxis
Eosinophil chemotactic substance
Neutrophil chemotactic substance
Heparin
Platelet activating factors

10. Dilatation of local blood vessels
Attraction of eosinophils and neutrophils to the reactive site.
Increased permeability of the capillaries with loss of fluid in the tissues.
Contraction of local smooth muscle.

11. Symptoms Compliment system is not activated.
Edema
Erythema
Itching
Compliment system is not activated.
Genetically passed from parent to child.

12. Clinical Manifestations
Anaphylaxis
Allergen is injected directly into circulation.
causes – peanuts,shell fish ,bee venom ,penicillin
Urticaria
Allergen enters specific regions of the skin
Hives--- Localized swellings
Hay fever
Allergen reagin reaction occurs in the nose
Asthma
Allergen reagin reaction occurs in the bronchioles of the lungs

13. Type II--- Cytotoxic Hypersensitivity
Occurs when antibody directed at antigens of the cell membrane activates compliment complex.
Membrane attack complex .
Compliment mediated lysis
Phagocytes are attracted towards the site.
Drugs
Infections
Blood transfusion reactions

14. Type III--- Immune complex Hypersensitivity
Antigen antibody complexes induce an inflammatory response in the tissues.
Reticuloendothelial system
Persist and are deposited in tissues
Persistent microbial or viral infections
Joints (arthritis)
Kidneys (nephritis)
Blood vessels (vasculitis)

15. Type IV– Delayed Reaction Allergy
Activated T cells
Poison Ivy
Contact dermatitis
Graft rejection