Leukocyte deformability--a comparison between different methods for separation of rat leukocytes from whole blood.

The deformability of rat leukocytes isolated by three different methods (Ficoll-Sodium Metrizoate, Ficoll-Hexabrix and Percoll) was studied with micropipette technique. The internal diameter of the micropipette tip was 4.0 microns and a constant aspiration pressure of -15 cm H2O was suddenly applied. The time course of deformation of the cells was analysed with video technique. The rat leukocytes showed the same viscoelastic deformation pattern as has been described earlier for human leukocytes. There was no significant difference in deformability between the three different lymphocyte (LC) fractions or between the two different polymorphonuclear granulocyte (PMN) fractions that were studied. The initial, rapid phase deformation was similar for LCs and PMNs, whereas the PMNs showed a considerably slower second phase deformation. This difference between LCs and PMNs is probably due to the larger size of the PMNs and the larger adhesive shear stresses acting on these cells. It is concluded that the three methods used for separation of rat leukocytes are equivalent in respect to the deformability of the cells produced.