R-848 leads to the retention of PBMCs in all peripheral organs. CFSE-stained spleen cells were adoptively transferred into animals that had been pretreated with PBS (A) or R-848 (B). Thirty minutes after transfer, blocking reagents to E- and P-selectin were injected, inhibiting further emigration to peripheral organs. An additional 30 (□) or 180 minutes (▪) later, animals were killed and the blood as well as peripheral organs were analyzed for the presence of adoptively transferred cells. The amounts found after 30 minutes were set to 100%, and the results after 180 minutes were calculated relative to this amount. In PBS-treated animals cells leave peripheral organs and home to the spleen, while in R-848-treated animals cells remain attached to all major peripheral organs with no obvious enrichment in the spleen.