Cytotoxic Hypersensitivity (Type II)

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Cytotoxic Hypersensitivity (Type II)
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Type II

• Cytotoxic hypersensitivity
• Reaction time is minutes to hours
• mediated by antibodies of IgM or IgG
• class and complement
• Phagocytes and NK cells may also play a role
  (ADCC).
• Diagnostic tests include detection of
• circulating antibody against tissues involved and
  the presence of antibody and complement in the
  lesion (biopsy) by immunofluorescence
• Directed against cell surface or tissue antigen
• The reaction may be local

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Some diseases caused by Type II

• Transfusion reactions
• Autoimmune Hemolytic anemia
• Hemolytic disease of newborn
• Drug induced hemolytic anemia
• Autoimmune thrombocytopenia
• Pemphigus vulgaris(desmoglein )
• Goodpastures syndrome
• Myasthenia gravis
• Graves disease
• Insulin resistant diabetes
• Pernicious anemia
• others

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Drug-Induced ReactionsAdherence to Blood
Components
blood cell adsorbed drug or antigen drug
metabolite

antibody to drug
complement
lysis
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Drugs that can cause this type of hemolytic
anemia include

• Cephalosporins (a class of antibiotics)
• Levodopa
• Methyldopa
• Penicillin and its derivatives
• Quinidine
• Some nonsteroidal anti-inflammatory drugs
  (NSAIDs)

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Hemolytic Disease of the Newborn
first birth
post partum
subsequent
RhD negative mother
anti-RhD
RhD positive red cells
B cell
Lysis Of RBCs
RhD positive fetus
RhD positive fetus
anti-RhD
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Type III(Immune complex mediated Diseases)

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Type III(Immune complex mediated Diseases)

• The reaction may be general (e.g., serum
  sickness) or may involve individual organs
  including skin ( Arthus reaction), kidneys,
  lungs, blood vessels , joints or other organs.
• It is mediated by soluble immune complexes
• The reaction may take few hours after exposure to
  the antigen
• The lesion contains primarily neutrophils

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Arthus reaction

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Immune complex mediated diseases

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Tissue injury mechanisms

• Antibodies may opsonize cells or activate the
  complement system
• Production of complement proteins that opsonize
  cells.
• These cells are phagocytosed and destroyed by
  phagocytes that express FcR and CR
• Main mechanism in autoimmune hemolytic anemia and
  thrombocytopenia and hemolysis in transfusion
  reactions.

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Tissue injury mechanisms

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Mechanisms of tissue injury
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Tissue injury mechanisms

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  gravis ???

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  ????? ?????? ???(cross reaction)

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Some diseases caused by immune complexes

• Systemic Lupus Erythematosus
• Nephritis
• Vasculitis
• Post streptococcal glomerulonephritis

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Mechanisms of tissue injury
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Mechanisms of tissue injury
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Pemphigus vulgaris