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Ashref Kassim, gr.2 PowerPoint PPT Presentation


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Type IV hypersensitivity– delayed hypersensitivity on the example of Mantoux test with a tuberculin reaction. Ashref Kassim, gr.2. Type IV cell-mediated hypersensitivity is a form of hypersensitivity mediated by specifically sensitized cells

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Ashref Kassim, gr.2

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Ashref kassim gr 2

Type IV hypersensitivity– delayed hypersensitivityon the example of Mantoux test with a tuberculin reaction

Ashref Kassim, gr.2


Ashref kassim gr 2

  • Type IV cell-mediated hypersensitivity is a form of hypersensitivity mediated by specifically sensitized cells

  • Whereas antibodies participate in type I, II, and III reactions, T lymphocytes mediate type IV hypersensitivity

  • Two types of reactions, mediated by separate T cell subsets, are observed

  • Delayed-type hypersensitivity (DTH) is mediated by CD4+ T cells


Ashref kassim gr 2

  • A classic delayed hypersensitivity reaction is the tuberculin or Mantouxreaction

  • Following exposure to Mycobacterium tuberculosis, CD4+ lymphocytes recognize the microbe’s antigens complexed with class II MHC molecules on the surface of antigen-presenting cells that process the mycobacterial antigens

  • Memory T cells develop and remain in the circulation for prolonged periods

  • When tuberculin antigen is injected intradermally, sensitized T cells react with the antigen on the antigen-presenting cell’ssurface, undergotransformation, andsecretelymphokinesthat lead to the manifestations of hypersensitivity

A standard dose is 5 tuberculin units (TU - 0.1 ml) is injected intradermally (between the layers of dermis) and read 48 to 72 hours later.


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