Enzyme release and morphological changes in leukocytes induced by mechanical trauma

Area of Science:

• Biomedical Engineering
• Cell Biology
• Hematology

Background:

• Polymorphonuclear (PMN) leukocytes are crucial immune cells.
• Understanding PMN response to mechanical stress is vital for various applications.
• Previous studies have explored platelet responses to shear stress.

Purpose of the Study:

• To investigate the effects of in vitro mechanical trauma on PMN leukocytes.
• To quantify enzyme release and morphological changes in PMNs under varying shear stress levels.
• To compare PMN sensitivity to mechanical trauma with that of platelets.

Main Methods:

• Exposing whole blood to controlled shear stress levels (75-600 dyn/cm2) for 10 minutes.
• Measuring enzyme release from azurophilic and specific granules.
• Assessing leukocyte count and rupture using Wright-stained blood films.
• Evaluating PMN morphology via transmission electron microscopy.

Main Results:

• Enzyme release and PMN rupture occurred at shear stresses between 75 and 150 dyn/cm2.
• Leukocyte count decreased slightly, while ruptured cell numbers increased significantly at these stresses.
• Higher shear stresses (600 dyn/cm2) led to marked cell destruction and distinct morphological alterations in intact PMNs.
• Intact PMNs showed fewer granules, more vacuoles, and condensed chromatin at high stress.

Conclusions:

• PMN leukocytes release enzymes and undergo morphological changes when subjected to mechanical trauma in vitro.
• PMN morphology and function are highly sensitive to shear stress, comparable to platelet sensitivity.
• These findings have implications for understanding blood cell behavior under mechanical forces.