Objectives: To examine (1) the effects of trauma on changes in neutrophil L-selectin and CD11b expression and on the levels of soluble L-selectin and (2) whether these alterations are different on leukocyte subpopulations in those patients who develop multiple organ dysfunction syndrome.
Materials and methods: Twenty patients with Injury Severity Score (ISS) > or = 16 and 15 patients with ISS score < 16 were studied. Arterial blood were collected serially after injury. The staining of leukocyte surface adhesion molecules was performed with antibodies against L-selectin and CD11b. Positive cell count and mean fluorescence intensity were determined by flow cytometry. Soluble L-selectin was measured using enzyme-linked immunosorbent assay.
Results: In patients with ISS > or = 16, neutrophil L-selectin expression showed an immediate increase, reaching peak levels between 3 to 4 hours after injury (p < 0.05 vs. patients with ISS < 16), followed by a gradual decrease. Plasma levels of soluble L-selectin reached peak levels at 6 hours after injury. However, in patients with ISS < 16, minimal changes in L-selectin expression and soluble L-selectin were observed. Neutrophil CD11b expression showed an immediate increase for the first 3 hours followed by a gradual increase up to 24 hours after injury. In patients who developed multiple organ dysfunction syndrome, CD11b both on neutrophils and lymphocytes remained elevated for 120 hours.
Conclusions: These findings suggest that acute neutrophil activation is an early event after trauma and may be implicated as "a vulnerable window" for leukocyte-mediated end organ injury.