Interaction of PF4 with different chemokines. Chemokines (3 μg) were applied onto a nitrocellulose membrane and incubated with PF4 (1 μg/mL). PF4 was detected by horseradish peroxidase (HRP)–conjugated secondary antibodies and enhanced chemiluminescence. Of 3 comparable experiments, 1 representative is shown (A). Representative surface plasmon resonance (SPR) sensorgrams of RANTES and E26A-RANTES (both 2.5 μM) binding to immobilized biotinylated PF4 on a streptavidin-coated C1-sensorchip (B). RANTES (solid squares), E26A-RANTES (triangles), Nme-7T-RANTES (dots), and ⁴⁴AANA⁴⁷ RANTES (open squares) were injected at 0.125, 0.25, 0.5, 1, or 2 μM, and equilibrium responses are shown as a function of concentration. Solid lines represent fits with a single site binding model (C).