A circulating factor modulates apoptosis of lymphocytes and monocytes after multiple trauma

Introduction

The advent of multiple trauma is accompanied by lymphopenia often due to apoptosis. This may be due to the existence of a circulating factor modulating apoptosis. The presence of such a factor in the serum of patients was assessed.

Methods

Serum was sampled at standard time intervals from 21 patients bearing multiple injuries and admitted to the ICU. Peripheral blood mononuclear cells (PBMCs) were isolated from five healthy volunteers after gradient centrifugation over Ficoll. PBMCs were stimulated overnight in a 96-well plate with 0.1 ml sampled serum. The percentage of annexin-V⁺/PI^-/CD4⁺ cells and annexin-V⁺/PI^-/CD14⁺ cells were estimated by flow cytometry. Results were compared with those obtained after cell incubation with serum of healthy volunteers.

Results

Median induction of apoptosis of CD4 lymphocytes and of CD14 monocytes after incubation with serum of healthy volunteers was 1.89% and 30.56%, respectively. Median percentages of apoptotic CD4 lymphocytes and CD14 monocytes of PBMCs after incubation with patient's serum sampled on consecutive days after admission are shown in Table 1. Similar results for patients complicated with sepsis on the first day of its advent are also presented.

Table 1 Induction of apoptosis of PBMCs after incubation with patients' serum

Conclusion

Incubation with serum of patients with multiple trauma-induced apoptosis of CD4 lymphocytes and of CD14 monocytes. These data strengthen the hypothesis for the existence of a circulating factor inducing apoptosis after multiple trauma.