Enzymatic and ultrastructural properties of the plasma membrane in human leukemias, in non-Hodgkin’s lymphomas and in human lymphoblastoid cells

Abstract

We have showed that mononuclear cells of patients with primary immunodeficiency displayed a remarkable scattering of surface enzyme activities, whereas normal peripheral blood lymphocytes and non proliferating cells of patients with recurrent infections of the respiratory tract did not [1, 2]. Almost complete lack of correlations between ectoenzyme activities was also noted in immunodeficient cells, in contrast to a broad correlation level in control lymphocytes [1]. On this basis, an hypothesis was developed suggesting a dynamic rearrangements of integral and associated constituents of the plasma membrane in acute pathologic situations leading to a discrete enzyme expression. This view was strenghtened by an enzymatic analysis of blood and reticuloendothelial cell malignancies. Specific activity changes of the ectoenzymes were recorded in cells isolated from patients with acute lymphoblastic leukemia. Cellular immunologic phenotype was defined by conventional surface and cytochemical markers [3, 4]. The contribution of the surface enzyme analysis to the identification of differentiation stage and cell origin has been clearly documented by a recent report [5] showing that acute undifferentiated leukemia (AUL; Ia⁺, cALLA^-) could be distinguished into three groups owing to the expression of the plasma membrane enzyme γ-glutamyltranspeptidase (Glupase) and the soluble terminal transferase (TdT). Thus, a leukemic population at a given stage of differentiation expresses a surface immunologic phenotype accompanied by biochemical characteristics of their plasma membrane.