Ecl-bound carbohydrate structures are commonly found in membrane and serum glycoproteins of mammalian origin. This structural sialic acid substitution appears to prevent lectins from binding. This specificity provides an opportunity to isolate or isolate mammalian glycoproteins using agarose bound ECL. It has been reported that the lectin can be used to isolate human natural killer (NK) cells using negative selection screening techniques. NK cells appear to lack the surface sugar structure needed to bind ECL, and unlike other monocytes, it does not attach to a petri dish coated with ECL. Since this process involves negative selection screening techniques, a high recovery rate of active NK cells can be obtained. Adherent cells can also be recovered by culture in galactose or lactose. Biotinylated Erythrina cristagalli lectin has the right amount of biotin to provide the best staining properties for this lectin. The conjugated compound contains essentially no unconjugated biotin and is preserved with sodium azide.