Assessment of erythrocyte deformability by constant flow filtration technique

Abstract

When filtering red blood cells (RBC) resuspended into buffer at constant flow, the pressure-time curve is dependent on erythrocyte deformability (E.D) and also on the plugging of pores by RBC or leukocytes (WBC). To understand the influence of these 3 factors, we used an apparatus with: 1) a constant flow syringe (Bioblock) (1.56 ml/mn); 2) a pressure transducer (Statham P23 ID); 3) a recorder (Gould); 4) a 5 μm polycarbonate filter (Nuclepore) housed in a lucite block according to Usami & al.(1). Resuspensions of RBC from 4 to 14 % haematocrit with 0 to 600 WBC/mm3 were investigated. Results indicate that: 1/ The first inflexion point of the pressure-time curve (initial pressure leading to calculation of β) is related to the RBC’s deformability; 2/β is (in our experimental conditions) dependent on the WBC number; 3/β seems very sensitive to deformability changes as shown by rapid increases induced by osmolarity changes.