Trauma stimulates the synthesis of Gc-globulin

Abstract

Objective: Actin is the dominating intracellular protein and is released to the circulation after tissue injury. Gc-globulin is one of the plasma proteins responsible for removal of actin from the circulation. Recent studies have shown that the level of Gc-globulin is reduced shortly after trauma. Serial changes in Gc-globulin after severe injury have not been studied so far and could provide additional information about the role of Gc-globulin in the pathophysiological response to trauma. Design: Prospective, observational. Setting: Surgical intensive care unit in a university hospital. Patients: Thirty-eight patients were included in the study: 12 women and 26 men with a median age of 38 years (range 19–86) and a median Injury Severity Score (ISS) of 18 (range 6–45). Seven patients died, on day 5, 8, 8, 10, 10, 13 and 21, respectively. Interventions: None. Measurements and main results: The serum concentration of Gc-globulin (Gc_total) and the percentage of Gc-globulin bound to actin (Gc_%complexed) were measured daily for 1 week using rocket immunoelectrophoresis. Concentrations of free Gc-globulin (Gc_free) and Gc-globulin bound to actin (Gc_bound) were calculated from these analytical results. The concentration of Gc_total and Gc_complexed correlated significantly (r=–0.99, p<0.001) throughout the time period. After day 3 levels of Gc_%complexed normalised, whereas levels of Gc_total continued to increase above control values. The concentrations of Gc_total and Gc_free were significantly lower in non-survivors compared to survivors; p=0.005 and p=0.03, respectively. This was combined with an inverse correlation of Gc_bound between these two groups (r=–0.73; p=0.04). Conclusions: Severe injury results in a prolonged load on the extracellular actin scavenger system; more pronounced in patients who do not survive. Gc-globulin displays characteristics of an acute phase reactant, with supra-normal serum levels 1 week after severe injury. Serial measurements of Gc-globulin after trauma could prove to be a method of early identification of patients with increased risk of mortality.