Plasma levels of interleukin-1 receptor antagonist (IL-1ra) and severity of illness in patients with burns.

The present study was conducted to determine whether a plasma interleukin-1 receptor antagonist (IL-1ra) would reflect the severity of burn injury and to examine the relation between IL-1ra and the cytokines. We studied 24 burn patients in whom the total burn surface area (TBSA) accounted for at least 20% of the body surface, and in whom serial blood samples could be obtained beginning immediately after the burn injury. Plasma levels of IL-1ra were determined by enzyme-linked immunosorbent assay (ELISA). Plasma levels of tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-8 were also determined by ELISA. Endotoxin was measured by an endotoxin-specific synthetic substrate method. There was a significant correlation between the plasma levels of IL-1ra and TBSA during the first week following burn injury. The IL-1ra level was the highest immediately after the burn injury. The level decreased markedly thereafter, and again rose when infection occurred. The IL-1ra level was extraordinarily elevated in patients who developed concomitant sepsis, septic shock or the septic multiple organ dysfunction syndrome. The IL-1ra level on admission and the maximum IL-1ra level during the observation period were significantly higher in the patients who eventually died than in the survivors. There was a significant correlation between the level of IL-1ra and that of TNF-alpha, IL-6 or IL-8 during the observation period. No correlation was found between IL-1ra and endotoxin. The plasma IL-1ra level was closely correlated with the severity of inflammation and the clinical status of the burn patients, regardless of the infection. Results suggest that IL-1ra can serve as an index of the systemic inflammatory response syndrome (SIRS).