Differences in Surface Sialic Acid and Galactosyl Residues of Two Autologous Human Melanoma Cell Lines

Cell surface carbohydrate differences were observed between two human cell lines initiated from primary melanoma and metastasis of the same patient. Although total sialic acid content was similar in both cell lines, neuraminidase-released sialic acid was twice as high in metastatic cells than that of primary cells. One class of Concanavalin A binding sites with similar affinity constant was found in untreated and neuraminidase-treated cells in both cell lines. Before surface sialic acid release, the primary cell line expressed two classes of Ricinus lectin binding sites with high and low affinity; the cell line of metastatic origin had only one class of Ricinus lectin binding sites with low affinity. After neuraminidase treatment, the number of Ricinus lectin binding sites with low affinity increased two- or three-fold in both cell lines, whereas the high-affinity binding sites were not observed in primary cells. The present data indicated that differences in surface sialic acid level modified the Ricinus lectin binding in two human melanoma cell lines. However, the ability of the cells to bind Concanavalin A was not changed.