Whole blood tumor necrosis factor-alpha production and its relation to systemic concentrations of interleukin 4, interleukin 10, and transforming growth factor-beta1 in multiply injured blunt trauma victims

Abstract

Objective: To study the relation of whole blood endotoxin responsiveness to inhibitory mediators systemically released after severe blunt trauma.

Design: Prospective, observational study.

Setting: University trauma center.

Patients: Thirty-two patients with blunt trauma (mean injury severity score, 33 points).

Interventions: Standard emergency department, surgical care, and postoperative intensive care unit treatment.

Measurements and main results: Whole blood and serum were obtained immediately after admission to the emergency department (<8 hrs after trauma, denoted day 0) and on days 1, 2, 4, 6, 8, and 14 after trauma. Whole blood specimens were assayed for endotoxin-induced tumor necrosis factor (TNF)-alpha synthesis ex vivo and serum specimen were assayed for interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-beta1 concentrations. Moreover, the TNF-alpha inhibitory capacity of recombinant human (rh) IL-4, rhIL-10, and TGF-beta1 as well as the inhibitory capacity of patients' serum from days 0, 1, 2, 4, 6, 8, and 14 were tested on uninjured donors' whole blood. Cytokines were determined by ELISA. Whole blood endotoxin responsiveness in multiply injured patients was significantly reduced during the observation period and was found to be significantly related to the total inhibitory activity detected in the corresponding sera. Exchange of patients' serum for uninjured donors' or recovered patients' serum restored TNF-alpha production of peripheral blood mononuclear cells from multiply injured patients. Serum levels of IL-4 and IL-10 were not related to trauma patients' whole blood TNF-alpha production upon endotoxin stimulation, whereas TGF-beta1 concentrations were positively related. Compared with the apparent half-maximal inhibition concentrations determined, serum levels of TGF-beta1, IL-10, and IL-4 were 20- to 20,000-fold below the quantities required to explain the inhibitory serum activity in multiply injured patients on day 0.

Conclusions: Whole blood hyporesponsiveness to endotoxin in multiply injured patients is caused by soluble serum factors systemically released after trauma, whereas the intrinsic leukocyte function appears unaffected. Inhibitory mediators other than IL-4, IL-10, or TGF-beta1 are supposed to be of major biological relevance for the posttraumatic regulation of leukocyte function. Characterization of the causative suppressive mediators is supposed as a prerequisite for the development of immunologically based therapeutic approaches in critically ill patients.