Distribution of Ecto-5′-Nucleotidase in Plasmamembrane Subfractions of Human Lymphoblastoid Cells

Abstract

The starting point of this investigation was the observation of a simultaneous expression of high levels of ecto-5′-nucleotidase (5′-N) and the socalled common ALL-antigen (cALLA) on leukemic blast cells in the common form of acute lymphocytic leukemia (cALL) and in the socalled lymphoid blast crisis in chronic myelogenous leukemia (CML)(see contribution by Gutensohn et al in this volume). The question was asked whether this simultaneous expression was regulated exclusively at the gene level or whether in addition there exists some physical association of these surface antigens in the plasmamembrane. The enormous cell number needed for this study cannot be obtained even from a leukemic patient. Therefore the established human lymphoblastoid null-cell-line Nairn 1 was used as a model system. This cell typically expresses both cALLA and 5′-N.