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Enzyme release and morphological changes in leukocytes induced by mechanical trauma
Abstract:
Polymorphonuclear (PMN) leukocytes exposed to mechanical trauma in vitro will release enzymes both from azurophilic and specific granules at shear stress levels of between 75 and 150 dyn/cm2 for 10 min. In addition, at these shear stresses the leukocyte count in whole blood decreased only slightly and the number of ruptured leukocytes on Wright-stained blood films increased significantly. At higher shear stresses, enzyme release and leukocyte damage increased monotonically. Transmission electron microscopy evaluation of sheared PMNs revealed that remaining intact cells had minor morphological changes at stresses of 150 dyn/cm2. They were characterized by clublike cytoplasmic potrusions, spherical shape, and a circumferential distribution of cytoplasmic granules. At higher shear stresses (600 dyn/cm2) cell destruction was marked. Intact PMNs contained fewer cytoplasmic granules, a large number of vacuoles, and condensed nuclear chromatin. These studies show that PMN morphology and function are at least as sensitive to mechanical trauma as similar platelet alterations seen in other studies.
Insights
Mechanical trauma in vitro causes polymorphonuclear (PMN) leukocytes to release enzymes and rupture. Higher shear stress levels increase PMN damage and enzyme release, impacting cell morphology and function.
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.