Background: The aim of this study was to test the hypothesis that inhibitory substances circulating in the patient's serum after trauma might impair leukocyte function by evaluating the effect of such serum on cytokine release in a whole blood model.
Methods: Hip replacement surgery was considered a standardized musculoskeletal trauma, and seven women and three men undergoing elective total hip replacement were included in the study. Ex vivo lipopolysaccharide (LPS) and peptidoglycan (PepG) induced tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL-10) releases were measured in whole blood sampled preoperatively and added serum taken before, at the end of operation and at postoperative day 1 and 6. Saline was used as negative control to serum.
Results: LPS and PepG induced a significant release of TNF-alpha and IL-10 in whole blood. Addition of preoperative serum, postoperative serum or day 1 postoperative serum did not alter the LPS-induced release of TNF-alpha as compared with saline control. Addition of preoperative serum significantly increased the PepG-induced release of TNF-alpha as compared with saline control (p = 0.011). This increase was not significantly changed with addition of postoperative serum or day 1 postoperative serum. When serum from postoperative day 6 was added, both LPS and PepG induced expression of TNF-alpha was significantly reduced as compared with preoperative serum (p = 0.018 and 0.008, respectively). Preoperative serum also increased the PepG induced expression of IL-10 (p = 0.007) in relation to saline control, and this increase was not significantly changed by addition of postoperative serum or day 1 and day 6 postoperative serum. Neither of the serum samples altered the LPS induced expression of IL-10 as compared with saline control (p = 0.212).
Conclusion: Our data show that in trauma patients, serum expresses activity that inhibits LPS and PepG induced release of TNF-alpha in a whole blood model, and our study, then, corroborates the hypothesis that inhibitory substances circulating in the patients' serum after trauma impair leukocyte function.