Neutrophil CD64 expression as a longitudinal biomarker for severe disease and acute infection in critically ill patients

INTRODUCTION: Neutrophilic granulocytes express cluster of differentiation 64 (CD64) antigen upon activation. CD64 can be used as a marker of bacterial infection and sepsis. The goal of this study was to determine whether CD64 is a useful biomarker for critically ill patients and analyze longitudinal measurements with regard to outcome and sepsis severity.

METHODS: In this prospective observational study, CD64 analysis was performed daily until discharge from ICU or death. Demographics, clinical, laboratory data, and outcome defined as 28-day survival were recorded. Patients were included when admitted to the ICU with sepsis, severe sepsis, or septic shock and within 24 h from start of antibiotic treatment.

RESULTS: Hundred and fifty-five consecutive patients were enrolled. At baseline, a difference in CD64 of 2.26 (1.33-4.47) vs. 1.49 (0.89-2.24) (P = 0.004) was seen between patients with a positive culture and negative culture. CD64 at day 1 was higher with patients with septic shock when compared with sepsis (P = 0.012). No difference of CD64 between survivors and nonsurvivors was seen.

CONCLUSION: This study demonstrated that CD64 discriminates between critically ill patients with culture positive and negative sepsis and correlates with severity of disease. However, CD64 index is not a good predictor for 28-day mortality in the critically ill patient.