The effect of specific glycosidases on Ricinus communis agglutinin binding to cell surfaces of two tumor sublines. A comparative flow-cytometric study.

The effects of the sequential application of specific glycosidases on surfaces of living mammalian cells were studied with respect to their ability to bind the beta-galactoside-specific lectin, Ricinus communis agglutinin (RCA). Sialidase and beta-galactosidases from different sources were tested for their actions on two strains of mouse lymphoma cells differing markedly in their metastatic potential. Binding studies were performed by quantitative flow cytometry with fluorescent RCA, and numbers of specific binding sites and equilibrium association constants for the lectin on living cells were determined before and after the various enzyme treatments. Although the number of binding sites for native and sialidase-treated cells were almost identical for both cell strains, differences in the apparent affinity constants could be detected. Differences between the two strains became even more pronounced, also with respect to the number of binding sites, after treatment with beta-galactosidases from S. pneumoniae and from bovine testis. It is suggested that such combined strategies provide valuable tools for the differentiation of surface carbohydrate moieties on intact living cells, especially for comparative purposes.