Leucocyte filterability: comparing diluted blood with purified cell suspensions.

Current rheological trends in filtration studies involve purification of cell subpopulations in order to study near-homogenous populations of cells, and this means that time-consuming and possibly cell-damaging procedures are used. Filtration of diluted blood offers the possibility of determining the properties of subpopulations of cells with minimal cell manipulation. The filtration properties of granulocytes and lymphocytes result in their being detected as one kinetic population, and therefore a combined granulocyte/lymphocyte pore transit time is calculated. There was no significant change seen in the combined granulocyte/lymphocyte transit time over the normal range of differential count. Filtration of diluted blood is a more reproducible way of measuring granulocyte and lymphocyte filterability, because purification of these cells gives rise to more scatter and larger ranges in the measured pore transit time, and significant day-to-day variation. A combined granulocyte/lymphocyte transit time is therefore an acceptable and reproducible way of assessing leucocyte rheology in diluted blood, when the differential count lies within the normal range. If changes in the granulocyte/lymphocyte transit time are detected, then cell purification may yield additional information on the subpopulations. Therefore, particularly in pathological samples, a combination of these approaches will yield more information than either test alone.