Exposure by desialylation of myeloid antigens on acute lymphoblastic leukemia cells.

The 3-fucosyl-N-acetyllactosamine structure, a sugar sequence contained in the human milk oligosaccharide lacto-N-fucopentaose III, is recognized by most of the granulocyte-specific monoclonal antibodies (MoAb) reported in the literature, including the six MoAb from our laboratory. Blast cells from patients with acute myeloblastic leukemia (AML) displayed a heterogeneous reaction pattern when they were exposed to MoAb against this moiety, and the proportion of reactive cells in individual cell samples was highly variable. The intensity of the reaction was strongly enhanced by neuraminidase treatment of AML blasts, and reactive structures were exposed on previously negative AML blast cells. Surprisingly, this granulocyte-associated antigen was exposed by desialylation not only on malignant myeloid precursor cells but also on common acute lymphoblastic leukemia cells. No such effect was seen when normal peripheral blood lymphocytes, lymphocytes from patients with chronic lymphatic leukemia, or blast cells from patients with B-cell acute lymphoblastic leukemia, acute erythroid leukemia, and acute megakaryoblastic leukemia were treated with neuraminidase.