PMN derived MVs in vivo andex vivo. MVs were separated from serum, using the same conditions as applied for isolated PMNs. (A) Concentration of PMN derived MVs in serum of healthy donors (n = 6) or patients with clinically verified S aureus bacteremia (n = 12), measured by flow cytometry after staining with anti-CD11b and anti-CD177 antibodies. (B-E) MVs separated from serum were incubated with not opsonized S aureus for 30 minutes at 37°C in HBSS with gentle shaking. Interaction was followed by fluorescent microscopy at the end of incubation. (B) Representative image of MVs from healthy donors (of 35 similar images from 4 independent experiments), whereas panel C is representative of MVs from bacteremic patients (53 similar images from 6 independent experiments). Red shows CD11b positivity, green represents S aureus. Statistical analysis (with same criteria as in Figure 5) of microscopic images shows amount of aggregated MVs to all MVs (D), and amount of clumped bacteria to all bacteria (E). Bars show mean ± SEM; #P < .05.