Confirmation of accelerated apoptosis in patients with severe sepsis. (a) Phosphatidylserine externalisation on CD4+, CD8+ and CD19+ lymphocytes of patients with severe sepsis. The population of phosphatidylserine-positive lymphocytes was increased as compared with critically ill patients and healthy controls. *p < 0.05, **p < 0.01. (b) Representative histograms of caspase-3 activation. Intracellular active caspase-3 was stained with a phycoerythrin-conjugated monoclonal antibody. CD 4+ T-cells were selected via immunophenotyping in flow cytometry. Region M2 describes the population with activated caspase-3. (c) Detection of active caspase-3 in lymphocyte populations. In patients with severe sepsis the phosphatidylserine-positive lymphocytes (CD 4+ T-cells, CD 8+ T-cells, CD19+ B-cells) were increased as compared with critically ill patients and healthy controls. **p < 0.01, ***p < 0.001.