Macrophage depletion and microvesicle formation. (A) Control and FlnA^loxP PF4-Cre mice were injected with PBS- or clodronate-encapsulated liposomes to ablate macrophages. Blood was collected at indicated time points, and platelet count and size were analyzed by flow cytometry. Results are forward/side scatter dot plots of each condition and are representative of 4 independent experiments. Gates represent beads (R1), platelets (R2), and erythrocytes (R3). Note the appearance of a population of small microvesicles in clodronate-treated FlnA^loxP PF4-Cre mice (arrows). (B) Platelet counts increase and (C) platelet size decrease in FlnA^loxP PF4-Cre mice after clodronate-liposome injection. Platelet size is measured by forward scatter and expressed as arbitrary units. Data represent the mean ± SD (n = 4). *P < .05.