Characterization of leukocytes by filtration of diluted blood

From the known numbers and properties of normal blood cells, it is apparent that the analysis of the flow of diluted blood, through micropore filters, should allow calculation of the properties of leukocytes without the need for their prior purification. The number and transit time of a 'slow' leukocyte population can be deduced by fitting the flow, of diluted blood through 5 μm membranes over about 150 s, to the appropriate mathematical model, which is chosen by the use of a suitable statistical test the runs test. This population of leukocytes equates numerically with the monocyte population of normal blood; cells have a transit time, through 5 μm pores, of 27.7 ± 10.9 s. The remaining 'fast' leukocytes represent the sum of granulocytes and lymphocytes; their flow properties can be deduced from the measured initial flow rate of diluted blood and the estimated properties of the red blood cells. The properties of the red cells can be assessed from filtration of purified suspensions with any concentration of cells from 0.52 x 10⁹/ml to 3.0 x 10⁹/ml. The transit times for red cells and granulocytes/lymphocytes, in blood diluted with about an equal volume of buffer, are 1.36 ± 0.17 ms and 1.48 ± 0.33 s, respectively. The transit times of blood cells, through 5 μm pores, are therefore inversely related to their numbers in blood.