A Pilot Study Assessing the Utility of Quantitative Myeloid-Derived Suppressor Cell Measurements in Detecting Posttraumatic Infection.

OBJECTIVES

Biomarkers that facilitate earlier diagnosis of posttraumatic infection could improve outcomes by expediting treatment and mitigating complications, including sepsis. We hypothesized that circulating myeloid-derived suppressor cell (MDSC) counts could identify patients with posttraumatic infection.

DESIGN, SETTING, AND PATIENTS: We conducted a single-center, prospective observational pilot study of trauma victims who required greater than or equal to 48 hours of mechanical ventilation. Whole blood was collected and tested by flow cytometry.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

Samples were analyzed in real-time with an 11-parameter quantitative MDSC assay. Two physician adjudications of infection were performed through a blinded review of medical records. MDSC and other cell counts were compared between subjects with and without posttraumatic infection using non-parametric methods. Data are presented as medians (25th-75th percentile). The area under the receiver operating characteristic (ROC) curves were used to assess the accuracy of cell counts for diagnosing infection. Most subjects (n = 39) were male (79%) with a median age of 48 (interquartile range [IQR] 32-65), Injury Severity Score of 29 (IQR 21-41), and ICU length of stay of 13 days (IQR 8-19). Twenty-one (54%) developed an infection and 11 (28%) of the cohort died. We compared total MDSC (T-MDSC) counts closest to the day of infection diagnosis with the initial T-MDSC counts in subjects without infection. T-MDSC counts were higher in those with infection compared to those without infection (696 [368-974] and 304 [181-404] cells/μL, respectively; p < 0.001). Lymphocyte, neutrophil, and CD45+ leukocyte counts were not statistically different between the groups. The area under the ROC curve distinguishing those with infection from those without for T-MDSC was 0.83 (p < 0.001).

CONCLUSIONS

MDSC counts determined by quantitative whole blood flow cytometrics can detect posttraumatic infection and may be useful to guide further diagnostic testing in critically ill trauma victims.