MONOSIALOGANGLIOSIDES OF HUMAN MYELOGENOUS LEUKEMIA HL-60 CELLS AND NORMAL HUMAN-LEUKOCYTES .1. SEPARATION OF E-SELECTIN BINDING FROM NONBINDING GANGLIOSIDES, AND ABSENCE OF SIALOSYL-LE(X) HAVING TETRAOSYL TO OCTAOSYL CORE

Previous studies suggested that sialosyl-Le(x) (SLe(x)) is a ligand ex pressed in human neutrophils and myelogenous leukemia HL60 cells which binds to E-selectin and possibly P-selectin. However, clear data on s tructures of carbohydrate epitopes in these cells were lacking. A syst ematic study was therefore initiated, employing a large quantity of HL 60 cells (greater than or equal to 1200 mL packed) and human leukocyte s (approximate to 100 mL packed), Gangliosides were extracted, followe d by extensive fractionation and examination of the E- and P-selectin binding ability of each fraction. The following results were of partic ular interest: (i) Only monosialogangliosides having a polylactosamine core with >10 monosaccharide units (or >4 N-acetyllactosamine units) showed E-selectin binding under static conditions with thin-layer chro matography overlay technique employing P-32-labeled E-selectin-express ing CHO cells, (ii) Sulfate groups were not detectable in the binding fractions, and di- and trisialoganglioside fractions did not show E-se lectin binding under these conditions. (iii) None of the fractions sho wed P-selectin binding under a similar assay system using P-32-labeled P-selectin-expressing CHO cells. (iv) Major gangliosides of HL60 cell s were structures I-XI (shown in Table 1 of text), none of which showe d E-selectin binding under the above conditions. (v) SLe(X) gangliosid es having tetraosyl to octaosyl ceramide core, which are the major gan gliosides of epithelial tumors (shown in Table 2), were completely abs ent from HL60 cells and neutrophils, Isolation and chemical characteri zation of ganglioside structures I-XI are described in this paper.