The shear stress diffractometer Rheodyn SSD for determination of erythrocyte deformability II. Sensitivity to detect abnormal erythrocyte deformability

Abstract

Instruments for measurement of red blood cell deformability (RBC) should be sensitive to detect both a moderate reduction in cellular deformabiltiy of the entire RBC population and of a subpopulation of rigid RBC. The sensitivity of the laser diffractometer Rheodyn SSD was tested by treatment of normal RBC with increasing concentrations of glutaraldehyde, mixing of normal RBC with increasing percentages of rigid RBC, and by density separation of normal RBC. Maximum RBC elongation (at a high shear stress of 60 Pa) decreased from 60 to 8 when increasing the glutaraldehyde concentration from 0 to 0.004%. For every 10% of rigid RBC, mean RBC elongation decreased by about 10%. Density-separated RBC showed a typical deformation behavior: “top” cells were better deformable than “bottom” cells over the whole range of applied shear stresses. The results show that the Rheodyn SSD is a sensitive tool to detect abnormal RBC deformability.