Amino-derivatives of L-selectin ligand analogs: phosphonoester core polysaccharide (PPME) and fucoidin were biotinylated with the use of biotinyl-N-succinimide ester, and these biotinylated analogs b-PPME and b-fucoidin were demonstrated as useful tools to investigate the functional activity of L-selectins in cytospin preparations obtained from healthy human donors and from patients with chronic lymphocytic leukemia (CLL). The avidin/biotin system adds a new alternative to the application of the L-selectin ligand analogs (PPME, fucoidin) which have been formerly used as fluoresceinated, solid phase or immobilized probes.