Abstract

Exit of water from mixed populations of human leukocytes and from leukemic cells isolated from peripheral venous blood was measured under an osmotic gradient by densimetric methods, and the permeability coefficient, Lps was calculated. All cells behaved as osmometers. The MCV varied linearly with the reciprocal of the osmotic pressure. No distinction between lymphocytes and granulocytes could be made in mixed populations with 40% to 90% granulocytes. However, smaller cells had significantly lower permeability coefficients than larger cells. Average Lp of cells isolated from 11 individuals with acute and chronic granulocytic leukemias was significantly lower than normals. In contrast, permeability coefficients were normal in four cases of lymphosarcoma and one of Hodgkin's disease. In eight cases of chronic lymphocytic leukemia, coefficients were lower than the overall average for normals, but the difference could be attributed to the smaller volume of the predominant lymphocyte population. In summary, membrane permeability to water may serve to distinguish granulocytic leukemias from lymphocytic leukemias when clear morphologic criteria are lacking.