Rheology of Leukocytesa

Abstract

The rheological properties of human leukocytes (WBCs) have been studied by micropipette aspiration and filtration tests. A small aspiration pressure applied via a micropipette (diameter approximately equal to 3 micron) causes the WBC to undergo a rapid elastic deformation followed by a slow creep. The data can be analyzed with a viscoelastic model: an elastic element K1 in parallel with a Maxwell element (elastic element K2 in series with viscous element mu). Neutrophils and B lymphocytes are similar in K1, K2, and mu, but these values are higher for T lymphocytes. Treatment of neutrophils with colchicine decreases K2 and mu without changing K1, whereas cytochalasin B decreases all three coefficients; these results indicate the importance of cytoskeletal microtubules and microfilaments in WBC rheology. In the presence of Ca2+, WBCs form protopods which have increased viscoelastic coefficients. Inhibition of protopod formation with pentoxifylline is associated with an increase in WBC deformability. The ruffled surface of the apparently round WBC provides an area about twice that needed to enclose a smooth sphere of the same volume; this geometric feature plays an important role in whole WBC deformability tested through 4-5 micron filter pores or micropipettes. Because of its larger volume and higher cellular viscosity, each WBC is equivalent to approximately 700 erythrocytes in its tendency to block 5-micron channels. The rheology of WBCs has significant implications in their functional behavior, including flow through the microcirculation and interaction with endothelial cells.

Pleural fluid viscosity may help identifying malignant pleural effusions

“…Although WBC have a much higher cellular viscosity than RBC, 16 their role in pleural fluid viscosity was not evident in the exudates investigated in this study. Similar to joint disease, 17 inflammation of the pleura associated with infectious disease may reduce pleural fluid viscosity.…”

Effects of Leucocyte Depletion on Rheologic Properties of Human CPDA-1 Blood

“…During filtration, white blood cells and platelets are removed partly by trapping and partly because of activation and subsequent adhesion to the filter [25, 26]. Leucocytes have a much lower deformability than RBCs [27]and may, therefore, affect high shear viscosity to a greater extent than one would expect from their small number (1,000 times less than RBCs). The contribution of a normal leucocyte number to whole blood viscosity is thought to be small and clinically irrelevant, which changes dramatically in leukaemia [28, 29].…”

Deficiency of Src Homology 2-Containing Phosphatase 1 Results in Abnormalities in Murine Neutrophil Function: Studies inMotheatenMice

“…They fulfill this role by virtue of rapid and coordinated responses that include chemotaxis, phagocytosis, secretion of the contents of granules/vesicles, and production of reactive oxygen intermediates (1)(2)(3). These responses are initiated by the interaction of cell surface receptors with specific ligands found on microbial targets or in the inflammatory milieu that in turn elicit intracellular signaling pathways leading to biological responses (1)(2)(3). The critical importance of these signaling cascades in host defense is well illustrated by immune deficiency syndromes, such as chronic granulomatous disease (4) and deficiency of the small GTPase Rac-2 (5), in which defects in microbicidal functions render patients unusually susceptible to life-threatening infections.…”