Shear Rate-Dependence of Leukocyte Cytoplasmic Viscosity

Although leukocytes are few in number compared to red blood cells, they have a large volume and low deformability compared to erythrocytes, and so their influence on blood flow and oxygen delivery is disproportionate to their numbers. Leukocyte mechanical deformability has been shown to play an important role in cell retention in the capillaries during ischemia or prior to tissue injury (Worthen et al., 1988; Erzurum et al., 1991; Harris and Skalak, 1993). In some cases of human leukemia, the number of leukocytes is elevated and a large fraction of immature leukocytes is found in the blood. Clinically, these cells are believed to be responsible for impairment of circulation to the eye, the central nervous system or the lungs, thus causing deleterious effects to the organs involved (Lichtman, 1984). Thus, it is of interest to have a more accurate picture of white cell deformability to more thoroughly understand their behavior and potential influence in the microvasculature.