Effect of contaminating leucocytes on erythrocyte filterability

Abstract

Clinical studies from this department have convinced us of the effect of even small changes in blood leucocyte count on erythrocyte filterability. In diabetes mellitus (1), in normal pregnancy (2), and in clinical trials of drugs that alter the leucocyte count (3), we have found the results for positive-pressure erythrocyte filtration through the 5 μm diameter pores of polycarbonate membranes (Nuclepore) to be leucocyte dependent. Confirmation of this came from in vitro manipulation of the number of contaminating leucocytes in the test erythrocyte suspension to give residual leucocyte counts ranging from 0.08 to 1.6 × 10⁹/1 and from 1.9 to 16.1 × 10⁹/1 (4). Over both ranges a significant correlation (P<0.001) was found (Table 1) between the leucocyte count and all three methods of interpreting the positive-pressure time curves (initial pressure, final pressure, and the red cell filtration ratio). Thus, it was not possible to avoid leucocyte effects by removing some, but not all, leucocytes or by interpreting the pressure-time curves in a different way (4).