Effect of mechanical deformation on structure and function of polymorphonuclear leukocytes

Area of Science:

• Cellular Biology
• Immunology
• Physiology

Background:

• Polymorphonuclear leukocytes (PMN) are crucial immune cells.
• Their passage through pulmonary capillaries involves mechanical stress.
• Understanding PMN response to deformation is key to pulmonary physiology.

Purpose of the Study:

• To investigate the effects of mechanical deformation on human PMN.
• To determine if PMN deformation influences their functional and structural properties.
• To assess the relevance of these changes to PMN transit in pulmonary capillaries.

Main Methods:

• Human PMN were mechanically deformed by filtration through 5- or 3-micron polycarbonate filters.
• Morphometric analysis assessed cell shape and cytoskeletal changes.
• Flow cytometry evaluated cytosolic Ca2+ concentration, F-actin content, and surface marker expression (L-selectin, CD18, CD11b).
• Cells were also primed with N-formyl-methionyl-leucyl-phenylalanine before filtration.

Main Results:

• PMN deformation was observed, persisting longer after 3-micron filtration.
• Transient increases in cytosolic Ca2+ and F-actin content were noted post-filtration.
• CD18 and CD11b expression increased after 3-micron filtration.
• Priming increased CD11b expression following filtration.
• No significant change in L-selectin expression or hydrogen peroxide production was observed.

Conclusions:

• Mechanical deformation of PMN induces structural and functional alterations.
• These changes, particularly increased Ca2+ and CD11b expression, may impact PMN behavior in pulmonary capillaries.
• The findings suggest that PMN deformation plays a role in their pulmonary microvascular transit.