The chemokines MDC, TARC, and SDF-1 rapidly potentiate platelet aggregation under high-shear flow conditions.

Washed platelets were exposed in the quenched-flow system (10 to 35 dyn/cm², “Materials and methods”16 20) to: (A) SDF-1 alone (0.5 μg/mL, ○), ADP alone (0.1 μM, ■), or SDF-1 combined with ADP (●); (B) MDC alone (0.5 μg/mL, ⋄), ADP alone (0.05 μM, ■) MDC combined with ADP (♦); (C) TARC alone (0.5 μg/mL, +), ADP alone (0.05 μM, ■), TARC combined with ADP (*); (D) SDF-1 (0.5 μg/mL) potentiation at low (0.05 μM) and high (10 μM) ADP levels; SDF-1 alone (▪), low ADP alone (▵), and low ADP combined with SDF-1 (▴); high ADP alone (○) and high ADP combined with SDF-1 (●). (E) SDF-1 potentiation at low (0.005 U/mL) and high (5 U/mL) thrombin levels. SDF-1 alone (▪); low thrombin (▿), and low thrombin combined with SDF-1 (▾); high thrombin alone (○), and high thrombin combined with SDF-1 (●). Aggregation is expressed as percentage platelet singlets remaining at each reaction time, as detected by resistive-particle counting. Data are typical for 11 experiments with SDF-1 and for 3 to 4 experiments with MDC and TARC. Experiments were carried out at 37°C as described in “Materials and methods.”