Effect of CCX8037 on the migration of CD11b+splenocytes into the joints. Cell Tracker Orange CMTMR-labeled CD11b+ splenocytes from CIA mice (1 × 107) were adoptively transferred into each recipient CIA mouse on day 9 after the second immunization. The recipient mice were treated with CCX8037 (10 mg/kg in 1% hydroxyprophyl methylcellulose) or vehicle 24 hours, 12 hours, and 30 minutes before the transfer, and 12 hours after the transfer. Twenty-four hours after the transfer, ankle joints were harvested and examined for migrated cells under a fluorescent microscope. The total number of labeled cells in three fields of vision was counted in the synovial tissue between the tibiotalar and transmetatarsal joints (n =5) at x20 magnification. Horizontal bars indicate the mean of each group. *P <0.001 versus vehicle. CCX8037, CC chemokine receptor (CCR) 9 antagonist; CIA, collagen-induced arthritis; CMTMR; 5-(and-6)-(((4-chloromethyl) benzoyl) amino) tetramethylrhodamine.