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Hypersensitivity
This document discusses hypersensitivity, classifying it into four types based on mechanisms. Type 1 is anaphylaxis caused by IgE antibodies binding to mast cells. Type 2 is antibody-dependent cytotoxicity. Type 3 involves immune complex deposition in tissues. Type 4 is cell-mediated delayed hypersensitivity. The types are distinguished by their pathophysiology and examples are given of conditions that fall under each type along with associated symptoms and treatments.
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Introduction by V Naveen Sahith on hypersensitivity and its significance in microbiology.
Presentation outline covering introduction, classification, symptoms, and treatment.
Hypersensitivity is a dangerous immune reaction causing severe symptoms, occurring immediately or delayed.
Hypersensitivity classified into 4 types by Gell and Coombs based on mechanisms: Types 1-4.
Involves B-cells producing IgE antibodies triggering severe allergic reactions via mast cell degranulation.
Symptoms include vasodilation, low blood pressure, swelling, cardiac arrest, and hay fever.
Treatment options include hyposensitivity (IgG), mast cell stabilizers, and epinephrine.
Type 2 involves antibodies binding to cell antigens, leading to cytotoxicity, e.g., blood transfusion reactions.
Involves immune complex formation that can cause tissue damage; symptoms include rheumatoid arthritis.
Delayed hypersensitivity reaction leads to inflammation and tissue damage; treated with corticosteroids.
Key references include 'Immunology' by Kuby and other immunology and microbiology sources.
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Hypersensitivity
- 1. HYPERSENSITIVITY BY V NAVEEN SAHITH MScMICROBIOLOGY
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- 3. INTRODUCTION • Hypersensitivityis the violent reaction of the Immune system leading to severe symptoms and even death. • Immune response is always directed towards protect the human body. But in hypersensitivity the immune response become dangerous to human • Hypersensitivity can bring it’s symptoms either immediately with in minutes or in delayed state after 24 to 48 hours
- 4. CLASSIFICATION • P.G.H.Gelland R.R.A. Coombs proposed a Classification scheme in which Hypersensitivity reaction are divided into 4 types on the basis of mechanisms H.Type -1 (Antibody –mediated) H.Type -2 (Antibody-mediated) H.Type -3 (Immune complex- mediated) H.Type -4 (Cell- mediated)
- 5. Type -1(Anaphylaxis) •In type 1 hypersensitivity, B-cells are stimulated (by CD4+TH2 cells) to produce IgE antibodies specific to an antigen. •This class of antibody high affinity to FC receptors on the surface of tissue mast cells and blood basophils. •Mast cells and basophils coated by IgE antibodies are “sensitized".
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- 7. A later exposureto the same allergen cross- link The membrane bound IgE on sensitized mast cells and basophils causing degranulation
- 8. SYMPTOMS:- • Vasodilation •Low blood pressure • Swelling of throat and tounge • Cardiac arrest leads to Death • Hay fever
- 9. TREATMENT:- • Hyposensitivity(IgG) •Stabilizing Mast cell – Isoprenaline, Sodium chromoglycate • Epinephrine
- 10. Type -2(Antybody - dependent) • In type 2 Hypersensitivity is due to the interaction of antibodies and cell associated antigens • When antibodies bind to antigens located on surface of the cell become cytotoxic • IgG Antibodies are involved in type 2 Hypersensitivity eg:- Mismatch blood group transfusion Erythroblastosis foetalis
- 12. Type –3 (Immune complex- mediated) • The reaction of antibody with antigen generates Immune complexes • Generally this complexing of antigen with antibody facilitates the clearance of antigen by phagocytic cells. But However, Large amount of Immune complexes can leads to tissue damage
- 14. SYMPTOMS:- • Rheumatoidarthritis • serum sickness TREATMENT:- •Corticosteriods • Antihistamine
- 15. Type -4(cell mediated) • When some subpopulation of activated TH cells encounter certain types of antigens. This reaction leads to inflammatory reaction cause tissue damage • It is delayed type Hypersensitivity
- 17. SYMPTOMS:- • Localcell damage • Inflammation • Redness of skin • Vesicle Eruption TREATMENT:- • Corticosteroid
- 18. Reference:- • Immunology- Kuby • Sara’s Immunology and microbiology