Glycosphingolipid expression in acute nonlymphocytic leukemia: common expression of shiga toxin and parvovirus B19 receptors on early myeloblasts

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Abstract
Glycosphingolipids (GSLs) are complex macromolecules on cell membranes that have been shown to play a role in neutrophil differentiation, activation, phagocytosis, and adhesion to both microorganisms and vascular endothelium. Because GSLs are often cryptic antigens on cell membranes, little is known regarding GSL expression in early myelopoiesis. To study the latter, myeloblasts were collected from patients with acute nonlymphocytic leukemia (ANLL) who required therapeutic leukocytopheresis for hyperleukocytosis. The neutral GSLs were isolated and identified by high-performance thin-layer chromatography (HPTLC), HPTLC immunostaining, gas chromatography, nuclear magnetic resonance, and fast atom bombardment–mass spectrometry. Like mature peripheral blood neutrophils, myeloblasts expressed glucosylceramide, lactosylceramide, and the neolacto-family GSLs, lactotriaosylceramide and neolactotetraosylceramide. Unlike neutrophils and chronic myeloid leukemia, most ANLL samples also expressed the globo-series GSLs, globotriaosylceramide and globotetraosylceramide. Globo GSL expression was strongly associated with a myeloblastic (ANLL M0-M2) and monoblastic phenotype (M5). A weak association was also noted with expression of either lymphoid (P < .10) or early hematopoietic markers (terminal deoxynucleotidyl transferase [TdT], CD34; P < .10). Globo-positive ANLL samples bound both shiga toxin and parvovirus B19 on HPTLC immunostaining. Based on these findings, we propose that neolacto and globo GSLs are expressed during early myeloid differentiation. Globotriaosylceramide expression on myeloblasts, and possibly myeloid stem cells, may have important implications for the use of shiga toxin as an ex vivo purging agent in autologous stem cell transplantation. Expression of globotetraosylceramide, the parvovirus B19 receptor, on myeloblasts may also explain the association between B19 infection, aplastic anemia, and chronic neutropenia of childhood.