Granulocyte colony-stimulating factor inhibits neutrophil apoptosis at thelocal site after severe head and thoracic injury

Background: Tissue injury from mechanical trauma often leads to secondary o rgan failure. Local accumulation of neutrophils and excessive release of to xic metabolites through inhibition of neutrophil apoptosis may be responsib le for capillary leakage and irreversible damage of resident cells of injur ed tissues. Methods: The purpose of this study was to examine the presence of apoptosis -inhibiting factors at the local site of tissue injury. Cerebrospinal fluid (CSF) from patients with severe head injury (n = 10; Abbreviated Injury Sc ale score, 4.5 +/- 0.2 points) and bronchoalveolar lavage fluid (BALF) from patients with serious chest trauma (n = 10; Abbreviated Injury Scale score , 4.1 +/- 0.1 points) were collected on days 1 and 3 after injury and compa red with CSF (n = 5) and BALF (n = 16) obtained from patients undergoing el ective orthopedic surgery. Neutrophils from healthy humans were incubated,v ith 10% of CSF or BALF for 16 hours. Neutrophil apoptosis was determined by flow cytometric analysis of propidium iodide nuclear staining, terminal de oxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labe ling, and May-Grunwald-Giemsa staining, Levels of granulocyte colony-stimul ating factor (G-CSF) in CSF and BALF were measured with enzyme-linked immun osorbent assay. Results: CSF and BALF from injured patients significantly inhibited spontan eous neutrophil apoptosis of healthy humans compared with control samples, whereas respiratory burst activity was enhanced (p < 0.05), Moreover, CSF a nd BALF from injured patients contained increased (p < 0.05) amounts of G-C SF, Neutralization of G-CSF in CSF and BALF from injured patients using mon oclonal anti-G-CSF antibody markedly (p < 0.05) reduced the apoptosis-inhib iting effect of those body fluids and decreased the respiratory burst. Conclusion: In patients with severe head or chest injury, G-CSF acts locall y as a strong inhibitor of spontaneous neutrophil apoptosis, which may caus e an increased destructive potential of neutrophils present in injured tiss ues.