Figure 6.

TNF does not alter CXCR4 expression on osteoclast precursors. Wild-type bone marrow cells were cultured with macrophage colony-stimulating factor for 3 days and then treated with PBS or TNF (10 ng/ml) for 24 hours. (a) Cells were harvested and stained with Phycoerythrin-labeled anti-c-fms and FITC-labeled anti-CXCR4 antibodies and were subjected to fluorescence-activated cell sorting analysis. c-Fms-positive cells were gated and the cell surface expression level of CXCR4 is shown in the histogram. (b) Cells were subjected to a transwell assay where various amounts of stromal cell-derived factor 1 (SDF-1) were added in the lower chamber. After 3 hours of incubation, migrated cells in lower chamber were harvested and measured in a microplate spectrofluorometer. Percentage of migrated cells was determined as in Figure 1. Data are representative of two independent experiments.