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Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)

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Topic updated on 05/24/17 5:25pm

Overview

Introduction
  • Antibody dependent cell mediated cytotoxicity (ADCC) is a cooperative response involving
    • binding of antibodies produced by B-cells to antigens
    • recognition of the constant fragment (Fc) by effector cells
    • release of damaging substances by effector cells
    • destruction of the pathogenic organism
  • ADCC is an interaction between innate and adaptive immunity that is important because
    • it allows innate immune effectors to recognize pathogens that
      • do not express pathogen associated molecular patterns (PAMPs)
      • hide these patterns from innate immune detection
      • otherwise subvert innate immune function
    • it composes a big part of the immune response to parasites
Activation
  • ADCC is activated by
    • specific binding of circulating antibodies to antigens using
      • IgG antibodies for the majority of responses
      • IgE antbodies for invasive helminths and other parasites
    • recruitment of immune cells by the constant fragment (Fc) of the antibody including
      • granulocytes such as
        • neutrophils
        • monocytes
        • eosinophils
      • other cells such as
        • macrophages
        • natural killer cells
  • ADCC is an adaptation of innate immune functions by the adaptive immune system
  • The specificity of ADCC is determined by the specificity of the antibody
Effector Mechanisms
  • After recognition of the coated pathogen a variety of cells are recruited to the pathogen
ADCC Effector Cells
Cell Type Function Mechanism
Macrophages
  • General destruction of recognized pathogens
  • Presentation of ingested antigens
  • Release of lytic enzymes and toxic substances
Natural killer cells
  • Detection of abnormal cells without MHC expression
  • Anti-tumor cell immunity
  • Release of granzyme and perforin proteins
Neutrophils
  • Antibacterial immunity
  • Release of lytic enzymes
  • Generation of reactive oxygen species
Eosinophils
  • Antiparasitic immunity
  • Release of major basic protein and other toxic substances

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Qbank (1 Questions)

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(M1.IM.32) A 27-year old male who works on an organic farm is diagnosed with infection by N. americanus, a helminthic parasite. Eosinophils require which antibody isotype to destroy these parasites via antibody-dependent cellular cytotoxicity? Topic Review Topic

1. IgA
2. IgE
3. IgM
4. IgD
5. IgG

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