FIG. 9.

CXCR4 down-regulation by the heparin-bound suppressive fraction. CD4⁺ cells (10⁶/ml) were incubated either with R10-50 (Ctrl), 15 to 30 μg of the 350 mM heparin-bound fraction [(1)], or SDF-1α (250 ng/ml), incubated for 45 min at 37°C, and then stained with monoclonal CXCR4-FITC antibody or control antibody (IgG2a). Staining was measured by FACS analysis. The data are representative of three or more experiments for primary CD4⁺ cells and H9 cells, using the 350 mM heparin-bound or the 40-kDa heparin-bound Superdex fraction (0.5 to 6 μg of protein).