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. 2013 May 22;208(5):761–770. doi: 10.1093/infdis/jit235

Figure 1.

Figure 1.

Methicillin-resistant Staphylococcus aureus (MRSA) exotoxin(s) promote platelet-neutrophil aggregate (PNA) formation independently of Panton-Valentine Leukocidin (PVL). Formation of PNA in human whole blood was quantitated by dual-color flow cytometry. A, Blood samples (100 µL) were preincubated with phycoerythrin-CD11b and fluorescein isothiocyanate–CD42b and then stimulated with 40 µL of bacteria-free log or stationary phase culture supernatant (CSN) from MRSA strain FPR3757 or an appropriate negative control (medium). Clostridium perfringens phospholipase C (r-PLC) served as a positive control. B and C, Stationary phase CSN from various pvl +(grey bars) or a pvl – (black bar) community-acquired MRSA clinical isolates (B) or stationary phase CSN from wild-type (WT) MRSA strain LAC (grey bar) and its isogenic pvl deficient mutant (LACΔpvl; black bar. The percentage of dual-positive CD11b/CD42b polymorphonuclear leukocytes was calculated using SYSTEM II flow cytometry software. Data represent the mean (±SD) of 4 samples from 2 independent blood donors. *P < .05, by the Student t test. Abbreviation: NS, not statistically significant.