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Quantification of Efferocytosis by Single-cell Fluorescence Microscopy
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Quantification of Efferocytosis by Single-cell Fluorescence Microscopy

Published on: August 18, 2018

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Rab17 mediates differential antigen sorting following efferocytosis and phagocytosis

Charles Yin1, Yohan Kim1, Dean Argintaru1

  • 1Department of Microbiology and Immunology and The Centre for Human Immunology, The University of Western Ontario, Schulich School of Medicine and Dentistry, London, ON, Canada N6A 5C1.

Cell Death & Disease
|December 23, 2016
PubMed

Insights

Macrophages prevent immune responses to apoptotic cells by altering antigen processing. Efferosomes, unlike phagosomes, avoid antigen presentation pathways by recruiting Rab17 and using recycling endosomes.

Area of Science:

  • Immunology
  • Cell Biology

Background:

  • Macrophages perform phagocytosis (pathogen engulfment) and efferocytosis (apoptotic cell clearance).
  • Both processes involve vesicle degradation but differ in immunogenicity, suggesting distinct antigen processing.
  • Antigen presentation by macrophages is crucial for adaptive immunity.

Purpose of the Study:

  • To investigate the differential processing and trafficking of antigens during phagocytosis versus efferocytosis.
  • To elucidate the molecular mechanisms underlying the non-immunogenic nature of efferocytosis.

Main Methods:

  • Mass spectrometry to analyze protein content of phagosomes and efferosomes.
  • Immunofluorescence microscopy to visualize vesicle trafficking and protein localization.
  • Tracking of engulfed material degradation and antigen presentation pathways.

Main Results:

  • Efferosomes, unlike phagosomes, lacked key antigen presentation machinery proteins.
  • Efferosomes recruited Rab17, a regulator of membrane recycling.
  • Degraded efferosome contents were directed via recycling endosomes, bypassing the MHC class II loading compartment.

Conclusions:

  • Macrophages actively prevent immune responses to apoptotic cells.
  • Preferential trafficking of efferocytosed material via recycling endosomes prevents antigen presentation.
  • This mechanism ensures efferocytosis is non-immunogenic, distinguishing it from phagocytosis.

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