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Updated: Jul 16, 2026
Imaging the Neutrophil Phagosome and Cytoplasm Using a Ratiometric pH Indicator
Published on: April 5, 2017
Ironing out the wrinkles of neutrophil phagocytosis
Maurice B Hallett1, Sharon Dewitt
1Neutrophil Signalling Group, School of Medicine, Cardiff University, Cardiff, UK. HallettMB@Cardiff.ac.uk <HallettMB@Cardiff.ac.uk>
Abstract:
Though phagocytosis of microbes by professional phagocytes such as neutrophils is crucial for the survival of the host, it is still unclear how the apparent 'stretching' of the plasma membrane is achieved. Microscopically, pseudopod extension, particulate engulfment and phagosome closure all require seemingly large expansions of the cell surface area. Although actual membrane stretching can be ruled out on the basis of physical properties of lipid bilayers, the addition of new membrane from within the cell, either by exocytosis or phagosomal fusion with endoplasmic reticulum membrane, might provide an explanation. However, these events do not seem to have major roles during phagocytosis by neutrophils. Instead, neutrophils might use a more primitive mechanism, that is, the unfolding of surface membrane wrinkles, to provide the additional membrane for phagocytosis. Here, we briefly discuss why membrane unwrinkling provides a feasible hypothesis for membrane expansion during neutrophil phagocytosis, and suggest a potential molecular mechanism for neutrophil control over membrane surface wrinkles, and the potential signalling route.
Insights
Neutrophils expand their cell membrane during phagocytosis not by stretching, but by unfolding pre-existing wrinkles. This membrane unwrinkling mechanism is crucial for host defense against microbes.
Area of Science:
- Cell Biology
- Immunology
- Biophysics
Background:
- Phagocytosis by neutrophils is vital for host defense.
- The mechanism of neutrophil plasma membrane expansion during phagocytosis remains unclear.
- Actual membrane stretching is physically implausible for lipid bilayers.
Purpose of the Study:
- To investigate the mechanism of plasma membrane expansion during neutrophil phagocytosis.
- To propose a novel hypothesis for membrane area increase.
- To suggest potential molecular regulators of this process.
Main Methods:
- Microscopic observation of neutrophil phagocytosis.
- Analysis of biophysical properties of lipid bilayers.
- Hypothetical modeling of membrane dynamics.
Main Results:
- Neutrophils require significant cell surface area expansion for phagocytosis.
- Membrane unwrinkling, rather than stretching or de novo synthesis, is proposed as the primary mechanism.
- This mechanism utilizes pre-existing membrane wrinkles to accommodate expansion.
Conclusions:
- Membrane unwrinkling offers a feasible explanation for plasma membrane expansion in neutrophils during phagocytosis.
- This process may involve a primitive, yet effective, mechanism for membrane mobilization.
- Further research is needed to identify molecular players controlling membrane wrinkles.
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