Related Experiment Videos
Experimental studies of membrane tethers formed from human neutrophils
Warren D Marcus1, Robert M Hochmuth
1Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA. warren.marcus@asu.edu
Abstract:
Membrane tethers (thin, cylindrical pieces of membrane) have been implicated in the rolling of neutrophils along the endothelium. In our studies, these tethers were formed from passive, stimulated (0.1 microM fMLP), and osmotically swollen (170-180 mOsm) human neutrophils; as well as neutrophils treated with 0.3 microM latrunculin A to disrupt the cytoskeleton. This tether formation was accomplished by micropipette suction of latex beads coated with antibodies to proteins on the neutrophil membrane surface. From plots of force versus velocity for the tether formation process, we calculated adhesion energies per unit area of the lipid membrane to the cytoskeleton and the viscous resistance (effective viscosity) that occurs during the formation of these tethers at finite velocity. Most of the properties of the neutrophil were altered once it had been treated as described above. We were also able to show mechanical reversibility of membrane tethers, as well as an unexpected formation rate at "high" tether forces. Since membrane tethers have been implicated in the rolling of neutrophils, then the changes in tether formation may ultimately alter how these cells roll.
Insights
Researchers studied how neutrophil membrane tethers form under various conditions. Altering neutrophil properties changed tether formation, potentially impacting how these cells roll along the endothelium.
Area of Science:
- Cellular mechanics
- Biophysics
- Immunology
Background:
- Neutrophil rolling on endothelium is crucial for immune response.
- Membrane tethers are hypothesized to play a role in this rolling process.
Purpose of the Study:
- To investigate the mechanical properties of human neutrophil membrane tethers.
- To understand how different neutrophil conditions affect tether formation and characteristics.
Main Methods:
- Membrane tethers were formed using micropipette suction of antibody-coated latex beads on human neutrophils.
- Neutrophils were studied in passive, stimulated (fMLP), osmotically swollen, and latrunculin A-treated states.
- Force-velocity relationships were analyzed to calculate adhesion energies and viscous resistance.
Main Results:
- Tether formation was achieved across various neutrophil conditions, including altered cytoskeleton and osmotic states.
- Calculations revealed adhesion energies and effective viscosity during tether formation.
- Mechanical reversibility and unexpected formation rates at high forces were observed.
Conclusions:
- Neutrophil treatment significantly alters membrane tether formation properties.
- Changes in tether mechanics may influence the rolling behavior of neutrophils on the endothelium.
- This study provides insights into the biophysical mechanisms governing neutrophil-endothelial interactions.