Analysis of lectin binding properties on human Burkitt's lymphoma cell lines that show high spontaneous metastasis to distant organs in SCID mice: the binding sites for soybean agglutinin lectin masked by sialylation are closely associated with metastatic lymphoma cells.

Abstract

Alterations in cell surface carbohydrates on human lymphoma cell lines with different spontaneous metastatic potential in the severe combined immunodeficiency (SCID) mouse model were analyzed. A difference in cell surface carbohydrates between high- (HBL-2, HBL-7 and HBL-8) and no- or low-(HBL-4, HBL-6, Daudi and Raji) spontaneous metastatic human lymphoma cell lines were analyzed on a FACScan using fluorescein-isothiocyanate (FITC)-conjugated lectins. The most consistent difference in lectin binding properties was found with soybean agglutinin (SBA) lectin. High-metastatic lymphoma cells (HBL-7 and HBL-8 cells) in vitro were found to bind the SBA lectin, but the cells in vivo (in primary tumors and metastatic tumors of SCID mice) showed considerably reduced SBA lectin binding. In addition, HBL-2 cells that almost did not bind SBA lectin in vitro and in vivo showed high spontaneous metastasis. Neuraminidase treatment revealed that SBA lectin binding sites were masked by sialic acid. On the other hand, no- or low-metastatic lymphoma cells in vitro and in vivo were found to bind SBA lectin. HBL-8 cell clones without SBA lectin binding showed high spontaneous metastasis to distant organs in SCID mice but HBL-8 cell clones with SBA lectin binding showed very low spontaneous metastasis. Sophora Japonica agglutinin (SJA) lectin is able to recognize the carbohydrates in common with SBA lectin, but it does not appear to be associated with metastatic capacity. These results suggest that the sialylation of particular carbohydrate residues on human lymphoma cells that are recognized by SBA lectin may be associated with the spontaneously metastatic capacity of human lymphoma cell lines in our SCID mouse model.