Effect of various stimulants on MV formation. Amount of formed MVs was followed on the basis of protein concentration (A-C) or flow cytometry after staining PMNs with anti-CD11b antibody (bacteria were not stained at all). (B-C) Stimulation of 9 × 10⁶/mL PMNs was carried out with 10⁸/mL opsonized S aureus (A-C) or 100nM PMA (B-C) or 1μM fMLF (C) for 20 minutes or 20 ng/mL TNFα for 30 minutes, 100 ng/mL LPS for 120 minutes or 100 ng/mL CXCL-12 for 5 minutes or 10⁸/mL S aureus with or without opsonization (C). In panel A the protein content of bacteria cosedimented with MVs is shown. In panel C and all later figures, this value has been subtracted. Bars show mean ± SEM, n = 4; #P < .05.