FIG. 4.

Migration of HOS-CD4 cells expressing X4 or R5 in response to chemokines. Different concentrations of SDF-1α (A) or MIP1-β (B) were placed in the lower wells of the chemotaxis chamber, and HOS-CD4/X4 (A) or HOS-CD4/R5 (B) cells were placed in the upper wells; the upper and lower wells were separated by a polycarbonate filter. The results are expressed as a chemotaxis index (CI), representing the fold increase of migrating cells in response to SDF-1α over the response to control medium. Significant cell migration (P < 0.05) was detected with ≥10 ng of chemoattractant per ml.