Detection of less deformable erythrocytes in suspensions: Evaluation of different rheological tests

Abstract

We have evaluated the sensitivity for rigid red cells of four different rheological tests: viscometry, red cell filtration, red cell elongation in a centrifugal field, and membrane aspiration into filter pores. Washed red cells were partially rigidified with 0, 0.01, 0.02, and 0.03 % glutaraldehyde for 30 min. The four tests had a similar sensitivity in measuring the gradual decrease of red cell deformability with increasing glutaraldehyde, with the exception of filtration, which was not sensitive for 0.01 and 0.02 % glutaraldehyde. The capacity of the tests to detect subpopulations of rigidified cells (0.03 % glutaraldehyde for 30 min) among normal red cells was analysed. The threshold for detection was between 10 and 30 % hardened cells. We conclude that the four rheological tests have a similar, good sensitivity for uniform populations of rigid red cells. Subpopulations of abnormal cells (below 30 %) are less well detected and should, therefore, be enriched in the suspension prior to rheological measurements.