Studies on red cell filterability: Significance of buffer media

Abstract

Blood cell deformability, most often measured as filterability through a polycarbonate filter, is a major determinant of the rheological properties of whole blood. In this study the influence of the suspension medium on the filterability of red cells was studied. We found a considerable variation in filterability between suspensions of red cells in media of different kinds. Thus the cells were suspended in phosphate buffered saline (PBS), pH 7.4, alone, in PBS with glucose 0.9 g/l, in PBS with bovine serum albumin (BSA) 2.5, 5.0 and 50 g/l, in PBS with BSA 50 g/l, fibrinogen 0.02 g/l and cholesterol 0.025 g/l, PBS with human plasma 19:1 (i.e. 1 ml plasma added to 19 ml of PBS) and in plasma alone. Photographs of cells in different suspension media were taken in the microscope. The filterability of red cells in PBS was greatly increased by addition of BSA and also the reproducibility was increased, especially at low concentrations of BSA. Red cells suspended in PBS alone, gave visually grossly distorted appearance rut the addition of BSA or human plasma, normalized the morphology of the cells. With human plasma, however, difficulties in reproducing the results were found. It is concluded that the choice of buffer medium is a critical point in blood cell filtration studies. The present study indicates that phosphate buffered saline with low concentration of bovine serum albumin might be a suitable choice.