The chemotactic activity of CXCL4L1 for human immature DCs is mediated via CXCR3. To demonstrate the involvement of CXCR3 in immature DC chemotaxis, cells were preincubated with CXCR3 ligands [(A) 30 ng/mL CXCL4, 30 ng/mL CXCL4L1, 50 ng/mL CXCL10, 20 ng/mL CXCL11, or dilution buffer (Ctrl)] or CXCR3-neutralizing Abs [(B) dilution buffer (Ctrl), 10 μg/mL monoclonal Ab (mAb), 28 μg/mL polyclonal Ab (pAb), or 10 μg/mL isotype control Ab] before addition to the Boyden microchamber. As chemoattractants, CCL3 (100 ng/mL), CXCL4 (30 ng/mL), CXCL4L1 (30 ng/mL), CXCL10 (50 ng/mL), or CXCL11 (20 ng/mL) were added to the lower wells. Results shown are the mean ± SD from 4 (A) or 3 (B) independent experiments. In panel A, statistically significant reduction of migration is indicated (*P < .05; Mann Whitney test).