type iv hypersensitivity reaction
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Type-IV Hypersensitivity Reaction
Dr. Arushi Agarwal
JR-1Pathology
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Hypersensitivity ReactionInjurious immune response
Exaggerated/inappropriate state of normal immune response with onset of adverse effects on the body
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TypesImmediate type
Type I : Anaphylactic Type II : Cytotoxic Type III : Immune Complex Mediated
Delayed Type Type IV : Cell-Mediated
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Type IV Hypersensitivity
Cell-mediated immune disorders
Caused by: Cytokines produced by CD4+T cells
Cell killing by CD8+ T cells
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Activation of CD4+T cellsCD4+T cells
Recognise peptides displayed by dendritic cells
Secrete IL-2
Proliferation of antigen-responsive T cells
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Differentiation of antigen responsive T-cells
Antigen presenting cells
TH17 SUBSET(Dominated by neutrophils)
TH1 SUBSET(Dominated by activated macrophages)
IL-12 IL-2, IL-3, IL-23
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Examples:• Tuberculin reactions• Granulomatous
inflammation• Contact dermatitis • Rheumatoid arthritis
• Multiple sclerosis• Inflammatory Bowel
Disease• Psoriasis
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T-cell mediated killing of targets involves:
• Perforins and granzymes
• Activation of apoptosis.
• Examples: Type 1 Diabetes Mellitus
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Thank you