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Time-lapse 3D Imaging of Phagocytosis by Mouse Macrophages
Published on: October 19, 2018
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Spatial Discrimination Limit Analysis of Macrophage Phagocytosis Between Target Antigens and Non-Target Objects Using
Maiha Ando1, Dan Horonushi1, Haruka Yuki1
1Department of Pure and Applied Physics, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
Micromachines
|November 27, 2024
Summary
Macrophages can engulf non-antigens attached to opsonized particles, suggesting the zipper mechanism is not essential for spatial discrimination in phagocytosis. This has implications for immune system targeting and medical applications.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Phagocytosis is a crucial immune process mediated by Fc gamma receptors (FcGR) and immunoglobulin G (IgG).
- The zipper mechanism, involving FcGR-IgG bonds, is believed to drive cell-membrane extension during phagocytosis.
- The capacity of this mechanism for spatial antigen discrimination remains unclear, particularly in mixed antigen/non-antigen clusters.
Purpose of the Study:
- To investigate the role and limitations of the zipper mechanism in phagocytosis.
- To determine if the zipper mechanism enables macrophages to selectively phagocytose antigens.
- To explore the spatial discrimination capabilities of macrophages when encountering mixed particle clusters.
Main Methods:
- Macrophages were fed mixtures of 2 μm IgG-coated and 4.5 μm non-coated polystyrene beads.
- Phagocytosis of these mixed clusters was observed.
- Microcapillary manipulation was used to hold non-opsonized particle parts during engulfment.
Main Results:
- Macrophages engulfed mixed clusters, including non-coated particles attached to opsonized particles.
- Non-coated particles were internalized even without direct zipper mechanism support, provided they were coupled to opsonized particles.
- When the non-opsonized part was manipulated, macrophages detached it, internalizing only the opsonized part.
Conclusions:
- An IgG-coated surface is essential for initiating phagocytosis via cell-membrane protrusion (zipper mechanism).
- Once initiated, phagocytosis can proceed with uncoated particles as followers, even without direct zipper mechanism support.
- Findings suggest potential for immune system misdirection by aggregated non-antigens and new medical applications for capturing targets via antigen aggregation.
