For in vivo experiments, male mice (8 month of age) received a single injection of LPS (500 ng/mouse or 20 ng/gm body weight) into the tail vein. Seven days after the injection, blood was collected as described above. For analysis of platelet antigen positive leukocyte sub-populations, flow cytometry was triggered with total leukocyte marker CD45-conjugated with allophycocyanin (CD45-APC). All CD45 positive events containing granulocytes, monocytes, lymphocytes and apoptotic bodies were separated by light forward and side scatter blot analysis and gated each sub-type of leukocytes based on their size. Each gate was verified using cell specific antibodies (CD11b for granulocytes, CD14 for monocytes and CD3 for T-lymphocytes and CD19 for B-lymphocytes. Differential leukocyte populations were then subjected to two-color analysis to differentiate leukocytes positive for phosphatidylserine and platelet antigen (annexin-V-FITC vs CD41-PE) from leukocytes negative for phosphatidylserine and platelet antigen. Percentages of positive events were calculated above the set threshold from isotype control antibody.