NEUTROPHILS ARE PRIMED FOR INCREASED ELASTASE RELEASE FOLLOWING MAJOR TRAUMA

Abstract

Introduction: Elevated plasma elastase levels have been reported following major trauma and isolated femoral fracture. Reamed femoral nailing has been shown to further increase plasma elastase levels. The aim of this study was to investigate neutrophil (PMN) priming for degranulation following major trauma and isolated long-bone pelvis fracture by assessing the ability of PMN to release elastase in-vitro in response to phorbol myristate acetate (PMA) an analogue of dia-cylglycerol (DAG) a component of the “second messenger” system.

Methods: 11 major trauma (ISS≥18) patients and 18 patients with isolated long-bone/pelvis fracture, were consented to enter the study. Patients in the isolated fracture group were further stratified depending upon the type of fracture stabilization they underwent [reamed nail (n=12), Ex-Fix (n=6)]. Blood samples were obtained on admission, at 24 hours post injury, at day 3 and day 5. 11 healthy volunteers were used as controls. PMN were isolated by dextran sedimentation and ficoll-hypaque density gradient centrifugation. The ability of PMN to degranulate was assessed by an elastase substrate assay.

Results: A significant increase in the capacity of PMN to release elastase in response to a PMA stimulus was seen in major trauma patients on admission as compared with healthy volunteers. However in patients with isolated long-bone/pelvis fracture, there was no difference in levels of elastase release. Further no difference in the ability of PMN to release elastase was seen between the reamed nail and Ex-Fix groups.

Conclusions: In conclusion we show that PMN are primed for increased degranulation (elastase release) following major trauma but not following isolated long-bone/pelvis fracture. These primed PMN are capable of increased tissue damage following major trauma thus increasing the risk of development of multiple organ failure.