CCL2 chemoattractant activity promoting monocyte migration, with or without chondroitin sulfate binding. Circulating monocytes derived from healthy controls (A, C, E) and systemic sclerosis (SSc) patients (B, D, F). (A, B) CCL2-induced monocyte migration in the presence or absence of chondroitin sulfate (CS) coating. Lower chambers of a TransWell® double-chamber system (Corning Incorporated, Corning, NY, USA) were coated with CS or vehicle, and CD14+ monocytes were applied to the upper chambers. (C, D) CCL2-induced monocyte migration on plastic plates precoated with serial concentrations of CS. (E, F) CCL2-induced monocyte migration on CS-coated plastic plates in the presence of anti-CCL2 mAb or control IgG. Relative monocyte migration was calculated as a percentage of migration in a control experiment using vehicle-coated wells without CCL2. All experiments were carried out in duplicate; the mean and standard deviation of three measurements is shown. Results from the two groups were compared using a Mann-Whitney U test. A representative result from four independent experiments is shown.