Effect of mechanical deformation on structure and function of polymorphonuclear leukocytes

Abstract

. Effect of mechanical deformation on structure and function of polymorphonuclear leukocytes. J. Appl. Physiol. 82(5): 1397-1405, 1997.-The present studies were designed to test the hypothesis that mechanical deformation of polymorphonuclear leukocytes (PMN) leads to functional changes that might influence their transit in the pulmonary capillaries. Human leukocytes were passed through 5-or 3-µm-pore polycarbonate filters under controlled conditions. Morphometric analysis showed that the majority of PMN were deformed and that this deformation persisted longer after filtration through 3-µm filters than through 5-µm filters (P , 0.05) but did not result in the cytoskeletal polarization characteristic of migrating cells. Flow cytometric studies of the filtered PMN showed that there was a transient increase in the cytosolic free Ca 21 concentration after both 3-and 5-µm filtration (P , 0.01) with an increase in F-actin content after 3-µm filtration (P , 0.05). Although L-selectin expression on PMN was not changed by either 5-or 3-µm filtration, CD18 and CD11b were increased by 3-µm filtration (P , 0.05). Priming of the PMN with N-formyl-methionyl-leucyl-phenylalanine (0.5 nM) before filtration resulted in an increase of CD11b by both 5 (P , 0.05)-and 3-µm (P , 0.01) filtration. Neither 5-nor 3-µm filtration induced hydrogen peroxide production. We conclude that mechanical deformation of PMN, similar to what occurs in the pulmonary microvessels, induces both structural and functional changes in the cells, which might influence their passage through the pulmonary capillary bed. neutrophils; deformability; F-actin; adhesion molecules THE PULMONARY MICROVESSELS restrict the passage of polymorphonuclear leukocytes (PMN) because of the discrepancy between the size of the PMN and the size of the lung capillary segments (5, 14, 15). Although erythrocytes [red blood cells (RBC)] have similar maximum dimensions to PMN, their greater deformability allows them to negotiate these restrictions more quickly (14). This results in pulmonary capillary transit times that are 60-100 times longer for PMN than for RBC, and this concentrates PMN with respect to RBC in pulmonary capillaries (14,15).Stimuli such as peptide chemoattractants, endotoxin, and smoking are known to decrease PMN deformability and further increase the concentration of PMN in pulmonary capillaries (6,18,27,30). Several in vitro filtration studies have measured the biophysical properties of PMN, particularly their size and deformability, and have shown that these factors determine the magnitude of PMN sequestration in the pulmonary microvessels (6, 18, 27, 30). The importance of the discrepancy between PMN and pulmonary capillary dimensions in causing PMN sequestration in the lung has also been demonstrated during forced expiratory maneuvers in which raised intra-alveolar pressure compresses alveolar microvessels and delays PMN (21). Studies in humans undergoing cardiac catheterization show that alveolar compression results in an immediate arteriovenous difference o...

Ceramide Generation in Situ Alters Leukocyte Cytoskeletal Organization and β2-Integrin Function and Causes Complete Degranulation

“…We confirmed this by assessing deformation after hydrostatic filtration through pores of defined size, which reorganizes and stabilizes the cytoskeleton (40). We found that unmanipulated PMNs forced through 8-pores, which are just larger than the cells, showed no morphologic effects of their passage through the filter, but cells pre-exposed to sphingomyelinase C displayed a prolate shape, showing they were larger than the pore and that they were unable to rapidly regain their shape after passage (data not shown).…”

In situ Microrheological Determination of Neutrophil Stiffening Following Adhesion in a Model Capillary

“…4 Decoupling the contributions of adhesion molecules and mechanical deformation is difficult. 12 Mechanical deformation alone, in the absence of any adhesion molecules, has been shown to cause pseudopod projection and stark changes in neutrophils biomechanical properties 27 while causing an increased adhesiveness by upregulating the integrins on the neutrophil surface. 12 Traditional methods for measuring the viscoelastic properties of materials require macroscopic samples and are thus incapable of providing localized rheological data for single cells.…”

“…12 Mechanical deformation alone, in the absence of any adhesion molecules, has been shown to cause pseudopod projection and stark changes in neutrophils biomechanical properties 27 while causing an increased adhesiveness by upregulating the integrins on the neutrophil surface. 12 Traditional methods for measuring the viscoelastic properties of materials require macroscopic samples and are thus incapable of providing localized rheological data for single cells. Partial aspiration into micropipettes can be used to assess whole cell mechanical properties 7,28 using single cells as samples, but it does not provide localized information for different regions inside the cell.…”

Dynamic deformation of migratory efferent lymph‐derived cells “trapped” in the inflammatory microcirculation

“…No cells were entrapped in the contralateral control microcirculation. Although physical entrapment may play a role in granulocyte sequestration (Hogg et al, 1992;Doerschuk et al, 1993;Wiggs et al, 1994;Kitagawa et al, 1997) and lymphokine-activated lymphocyte localization (Fisher et al, 1989) in the lung, lymphocyte entrapment does not appear to play a significant role in the delivery of lymphocytes to the oxazolone-stimulated skin.…”