Hypersensivity Reactions

Hypersensivity Reactions - Hypersensivity Reactions...

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Hypersensivity Reactions Allergies Greek = altered reactivity 1906 – von Pirquet coined term: hypersensitivity Hypersensitivity reactions – ‘over reaction’ of the immune system to harmless environmental antigens
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Definition Hypersensitivity refers to undesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normal immune system. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. Hypersensitivity reactions can be divided into four types: type I, type II, type III and type IV, based on the mechanisms involved and time taken for the reaction.
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Hypersensitivity reactions – originally divided into 2 categories: immediate and delayed In 1968 Coombs & Gell defined the 4 types used today Type I: classical immediate hypersensitivity Type II: cytotoxic hypersensitivity Type III: immune-complex mediated hypersensitivity Type IV:cell mediated or delayed hypersensitivity
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Hypersensitivity reaction depends on: 1) chemical nature of allergen 2) route involved in sensitization ie inhalation, ingestion, injection… 3) physiological state of individual / genetic potential
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Type I (Dr Koshak will take it in details) Common among population in developed
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Hypersensivity Reactions - Hypersensivity Reactions...

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