Influence of physicochemical factors on rheology of human neutrophils.

The effects of variations in temperature, pH, and osmolality on the rheological properties of human neutrophils were determined by studying the cell deformation in response to aspirational pressure applied via a micropipette. The time history of the deformation was analyzed by the use of a standard solid viscoelastic model consisting of an elastic element K1 in parallel with a Maxwell element (an elastic element K2 in series with a viscous element mu). With changes in temperature over a range of 9-40 degrees C, only mu varied inversely with temperature, while K1 and K2 did not show significant alterations. Variations in pH over the range of 5.4-7.8 did not significantly affect the viscoelastic coefficients, but K1 and mu rose at pH 8.4. An increase in osmolality caused all three coefficients to rise, but a decrease in osmolality had relatively little effect on the coefficients. These changes in response to physicochemical variations serve to provide insights into the viscoelastic properties of neutrophils and their possible roles in health and disease.