Chemotaxis effect of human CX3CL1-DDDDK (ab108577) in THP-1 Cells. Cell migration of THP-1 monocytic leukemia cells was evaluated in disposable 24 well transwell polystyrene membrane with 8µm size pores. 100ng, 500ng, 1,000ng, 2,500ng and 5,000ng of recombinant CX3CL1 were diluted in RPMI 1640 supplemented with 10mg/ml BSA, respectively. CX3CL1 samples were added to the lower chamber. THP-1 cells (0.5 X 10 6 cells per well), in the same media with ab108577, were added to the upper chamber. After 2 hour incubation at 37°C in 5% CO2 humidified atmosphere, migration cells in the lower chamber were counted. Migrated cells in two separate fields per well from duplicate wells were enumerated on a hemacytometer by means light microscopy.