Relationship of interleukin-10 plasma levels to severity of injury and clinical outcome in injured patients.

Interleukin-10 (IL-10) markedly inhibits lymphocyte and phagocytic functions, which are essential for an adequate immune response to invading microbes. Although various animal and clinical studies revealed an increased release of IL-10 during sepsis, alterations of circulating IL-10 after injury and potential relationships to severity of injury and clinical outcome are unknown. Injured patients (n = 417) showed elevated (p < 0.001) IL-10 levels throughout the observation period of 21 days compared with healthy volunteers (n = 137). Patients with severe injury (Injury Severity Score > or = 25 points) demonstrated significantly increased IL-10 levels compared with patients with minor trauma (Injury Severity Score < 25 points). Patients who died from injury or developed posttraumatic complications (sepsis, multiple organ dysfunction syndrome) revealed elevated IL-10 levels in comparison with injured patients with uneventful posttraumatic course. Thus, trauma causes an enhanced release of IL-10 dependent on the severity of injury. Because increased IL-10 levels are significantly related to posttraumatic complications, IL-10 may be involved in their pathogenesis.