Red cell membrane abnormalities in chronic myeloid leukaemia.

Chronic myeloid leukaemia (CML) is a clonal neoplasm that arises in a stem cell common to granulocytes and erythrocytes. Several abnormalities have been identified in the plasma membranes of granulocytes of CML patients, but to our knowledge no studies have been done on CML erythrocytes. We report here that CML erythrocyte spectrin becomes abnormal due to cross-linking of its two subunits via disulphide bonds. In addition, we show that this cytoskeletal defect in the erythrocytes is associated with loss of transmembrane phospholipid asymmetry. These observations, apart from demonstrating membrane abnormalities in CML erythrocytes, also provide strong support for the view that the asymmetric organization of phospholipids in the red cell membrane is maintained mainly by interactions between spectrin and aminophospholipids.