Automated measurement of neutrophil CD64 expression for diagnosing sepsis in critically ill patients

Although early identification of sepsis improves outcome, prompt and correct diagnostic remains often challenging. The expression of the high affinity immunoglobulin-Fc fragment receptor I CD64 on neutrophils is upregulated during acute inflammation. We here aimed at determining the usefulness of its rapid measurement in diagnosing sepsis.

Seventy-two consecutive patients were enrolled upon admission to Intensive Care Unit within a two-month period. Sequential determination of serum C-reactive protein (CRP) and procalcitonin (PCT) concentrations was obtained. The neutrophil CD64 index was measured using Accellix-CD64® device, an in vitro diagnosis system allowing for an automatic and standardized measure.

Serum concentrations of CRP and PCT as well as the neutrophil CD64 index were higher in septic patients compared to all others (P<0.05 for the three markers). Only CD64 index was an independent predictor of sepsis, though with modest sensitivity and specificity (78% and 70%, respectively). Repeat determination of CD64 index at day 2 correctly classified 85% of patients.

This prospective study demonstrates the moderate performance of the neutrophil CD64 index, assessed through the Accellix-CD64® device, in diagnosing sepsis in the critically ill patient. However, repeat measurements improve its accuracy and may help to predict ICU-acquired infections.