Aptamers as blocking agents. Aptamers, in this case composed of phosphorothioates, selectively bind to E-selectin that is presented on the surface of human endothelial cells. The aptamers serve as antagonist for the interaction to sialyl Lewis X on HL-60 cells, a human promyelocytic leukemia cell line, thereby inhibiting the adhesion of tumor cells by more than 75%.
