Sialylated glycolipid antigens on human leukemic cell lines

Many granulocyte-specific mouse monoclonal antibodies recognize the carbohydrate sequence 3-fucosyllactosamine, Ga 1 beta 1-4[Fuc alpha 1-3]GlcNAc, which occurs in cell-surface glycolipids and glycoproteins. In general, these antibodies bind to blast cells from most patients with acute myeloblastic leukemia, but not to those with acute lymphocytic leukemia. Neuraminidase treatment, however, increases exposure of this antigen on both myeloid and lymphoid cells. In the present study, the glycolipids from 13 lymphoid and nonlymphoid human cell lines were examined for the presence of unsialylated and sialylated 3-fucosyllactosamine sequences using a thin-layer chromatography immunostaining method. Nine of the cell lines were also tested by indirect immunofluorescence both before and after neuraminidase treatment. None of the six B-cell and T-cell lines had detectable neutral or sialylated glycolipid antigen. In contrast, six out of seven and five out of seven nonlymphoid cell lines had neutral and sialylated glycolipid antigens, respectively. These results agreed, in general, with those found by indirect immunofluorescence. They also represent the first direct demonstration of these sialylated glycolipids on human leukemic cells. Thus, in some cases increased antibody binding to neuraminidase-treated cells can be explained by the presence of sialylated glycolipid antigen.