Masking of Neutrophil Surface Lectin-Binding Sites in Chronic Myelogenous Leukemia (CML)

Abstract

We have conducted experiments to determine whether alterations in cell surface oligosaccharide residues might be related to altered granulocyte function in chronic myeloid leukemia (CML). Peripheral blood neutrophils from patients with Philadelphia chromosome-positive CML, patients with benign leukocytosis, and 18 normals were tested for leukoagglutination against concanavalin A (Con-A), peanut lectin (PNA), and limulin (LIM). Cells were also assayed for their ability to adhere to column-packed nylon fibers. Compared to normal, neutrophils from patients with CML (WBC 25–600,000/cu mm) showed reduced or absent agglutination with PNA, and increased reactivity to LIM. CML cells also showed distinctly decreased adhesiveness, with up to 50% passing through the nylon-fiber column; normals showed less than 5% nonadherent cells. The effluent subpopulation of less adhesive CML cells differed from those of the unfractionated suspension in showing a greater reduction of reactivity with PNA and Con-A and increased agglutination by limulin. In vitro treatment of granulocytes of CML patients with vibrio cholera neuraminidase (VCN) partially reversed the defect in adherence toward normal. VCN treatment of normal cells had little effect. These data suggest the possibility that in CML, sialic acid or hypersialylated glycoproteins may mask cell surface receptors that may mediate granulocyte adhesion. Similar inhibition of receptors involved in neutrophil margination and emigration from capillaries, and in retention of immature forms in the bone marrow, might account in part for altered granulocyte kinetics and function in CML.