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7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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Starting With That Great Name ,
Whose Help We Solicit . . .
7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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Presented By:
ASAD ALI SIYAL
Department of Biomedical Engineering ,
Mehran University of Engineering & Technology (MUET),
Jamshoro, Sindh, [email protected]
7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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Presentation Contents:
Hypersensitivity (Introduction)
Types
I (Immediate Hypersensitivity) II (Antibody Mediated Hypersensitivity)
III (Immune-Complex Mediated Hypersensitivity) IV (Cell-Mediated Hypersensitivity)
Summary
7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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INTRODUCTION
HYPERSENSITIVITY:
Hypersensitivity refers to excessive, undesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normalimmune system. Hypersensitivity reactions require a pre-sensitized(immune) state of the host.
Hypersensitivity reactions can be divided into four types:Type - I
Type - IIType - IIIType - IV
based on the mechanisms involved and time taken for the reaction.
7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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TYPE – I(Immediate Hypersensitivity)
- It is also known as immediate or anaphylactic hypersensitivity
- The reaction may involve skin (urticaria and eczema), eyes (conjunctivitis),nasopharynx (rhinorrhea, rhinitis), bronchopulmonary tissues (asthma) and
gastrointestinal tract (gastroenteritis).
- It cause “Immediate Allergic Reactions”, which may lead to anaphylaxis, shock,edema, dyspnea death
1) Allergen exposure2) IMMEDIATE phase: MAST cell DEgranulation, vasodilatation, vascular leakage,
smooth muscle (broncho)-spasm3) LATE phase (hours, days): Eosinophils, PMNs, T-Cells
Reaction Time: It takes duration of seconds to minutes.
7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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TYPE – II(Antibody Mediated Hypersensitivity)
-It is also known as cytotoxic hypersensitivity and may affect a variety of
organs and tissues.
- It is primarily mediated by antibodies of the IgM or IgG classes and
complement
- It results when antibodies are directed against antigens on the surface of
cells or other tissue components.
-These reactive antigens may be Intrinsic antigens or reactive antigen
Effects:
It can have a variety of detrimental effects , including inflammation,
opsonization and phagocytosis
Reaction Time:
It takes duration of minutes to hours. .
7/27/2019 Hypersensitivity_(Human Physiology)_Presentation_by Biomedical Association of Students for Excellence(BASE)
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TYPE – III(Immune complex-mediated hypersensitivity)
-It is also known as immune complex hypersensitivity.
•- It is mediated by soluble immune complexes. They are mostly of the
IgG class, although IgM may also be involved.
- Type III hypersensitivity diseases are some of the most common
immune-mediated diseases.
-In these diseases, complexes of antibodies and antigens in circulation
deposit in the vascular walls of blood vessels leading to inflammation.
- The reaction may be the pathogenic mechanism of diseases caused by
many microorganisms.
Reaction Time:
The reaction may take 3 - 10 hours after exposure to the antigen
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TYPE – IV(Cell-Mediated Hypersensitivity)
-Type IV hypersensitivity is also known as cell mediated or delayed type
hypersensitivity.
-The classical example of this hypersensitivity is tuberculin (Montoux)
reaction
-It is also involved in the pathogenesis of many autoimmune and infectious
diseases
- It can be classified into three categories depending on the time of onset
and clinical and histological presentation
1. T lymphocytes2. Monocytes
3. Macrophages
Reaction Time:
It takes 48 hours after the injection of antigen
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SUMMARY
Type - I Acute allergic reaction
Type - II Antibodies directed against cell surfaces
Type - III Immune complexes
Type -IV Delayed Hypersensitivity, e.g., Tb skin test
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