Mobilization of leukocytes in patients with severe sepsis and septic shock is associated with increased apoptosis, as detected by Annexin V binding

Objectives

To clarify whether mobilization of leukocytes during human severe sepsis and septic shock occurs independently of apoptosis.

Methods

Over a 6 month period, 33 patients with severe sepsis or septic shock were studied in the intensive care unit. Annexin V binding by leukocytes was determined daily using flow cytometry and FITC-labeled Annexin V. Transient leukocytosis, or peaks in leukocyte counts, were defined as individual increase of at least 30% within 2 days, followed by a decrease of at least 30% within the following 2 days.

Results

Nine, 14 and 10 peaks in neutrophil, monocyte and lymphocyte counts, respectively, were observed in 6, 9 and 10 patients; in all of these patients, increased Annexin V binding by neutrophils, monocytes and lymphocytes, respectively, by 69% up to 809% (median 215%), by 32% up to 973% (median 330%), and by 32% up to 4713% (median 224%), respectively, paralleled the neutrophil, monocyte and lymphocyte (in 13/14 episodes) peaks, respectively. During periods in which neutrophil, monocyte and lymphocyte numbers were stable, Annexin V binding was constant as well.

Conclusions

In conclusion, mobilization of leukocytes during severe sepsis and septic shock in critically ill patients is associated with increased apoptosis, as determined by Annexin V.