Early elevation of soluble CD14 may help identify trauma patients at high risk for infection

BACKGROUND: Elevated levels of soluble CD14 (sCD14) have been implicated in both gram-positive and gram-negative sepsis, and it has been associated with high mortality in trauma patients who become infected. METHODS: Eleven healthy volunteers and 25 adult trauma patients with multiple injuries and a mean Injury Severity Score of 32 participated. Whole blood was obtained at intervals. Immunohistochemistry was used to quantify membrane CD14 (mCD14), by flow cytometry and plasma levels of sCD14 by enzyme-linked immunosorbent assay. Analysis of variance and Student's T test with Mann-Whitney posttest were used to determine significance at p < 0.05. RESULTS: On posttrauma day 1, sCD14 was significantly different in the plasma of infected patients compared with normal controls (7.16 +/- 1.87 microg/mL vs. 4.4 +/- 0.92 microg/mL, p < 0.01), but not significantly different from noninfected patients. The percentage of monocytes expressing mCD14 in trauma patients did not differentiate them from normal controls; however, mCD14 receptor density did demonstrate significance in septic trauma patients (n = 15) versus normal controls on posttrauma day 3 (p = 0.0065). CONCLUSION: On the basis of our data, mCD14 did not differentiate infected and noninfected trauma patients, although trauma in general reduced mCD14 and elevated sCD14. Interestingly, 100% of patients who exceeded plasma levels of 8 microg/mL of sCD14 on day 1 after injury developed infections. Therefore, early high expressers of sCD14 may be at higher risk for infectious complications after trauma.