Flow cytometric analysis of binding of vWF to S. aureus.

Microorganisms (120 000 cells/mL) were incubated with FITC-vWF (150 μg/mL, 10 minutes at 21°C), then analyzed for binding by flow cytometry as described in “Materials and methods.” (A) Binding of vWF to 3 S. aureus strains (▴, Cowan 1; ▪, Newman; ●, 8325-4). (B) Inhibition of vWF binding to S. aureus strains by the addition of excess unlabeled vWF over FITC-vWF (200 μg/mL) (symbol denotation as in A). (C, D) Inhibition of vWF binding toS. aureus Cowan 1 (C) and Newman (D) by the addition of polyclonal anti-SPA (▪) and IgG (●) antibodies. Shown are means ± SD (n = 3). RF indicates relative fluorescence.