Characterization of neutrophil microparticles (MPs). Neutrophil MPs analyzed by electron microscopy (A-B) and flow cytometry (C-I): Representative scanning electron microscopy micrograph of spheroid MPs (A). MPs analyzed by transmission electron microscopy and show the presence of lipid bilayers (B). Fluorescence histogram of MPs (black) and beads (grey), demonstrating their size (C). MPs events were marked with 2 μM PKH26 a membrane marker (black) (D). Integrity of neutrophil MPs (E): Fluorescence histogram of MPs derived from neutrophils labeled with 20 μM CFDA (black) and activated with 2 μM calcium ionophore. Flow cytometry analysis of the surface protein expression of MPs derived from neutrophils activated with 2 μM calcium ionophore (F-I): MPs were incubated with isotype control antibodies (thick line) or specific antibodies (black). Polymorphonuclear degranulation marker CD66b (F). L-selectin (CD62L) (G). Phosphatidylserine (H): MPs were labeled with annexin V (AnV) in the presence (black) or absence (negative control- thick line) of calcium. Myeloperoxidase (I). MPs derived from neutrophils activated with LPS: events were labeled with anti-Myeloperoxidase (black) (J). The figure shows a representative experiment among three performed.