CD64, a marker of leucocyte activation kinetics after uncomplicated cardiac surgery

Introduction

The aim of this study was to assess the CD64 kinetics after normal cardiac surgery, an essential step to define the potential use of CD64 as an early and specific infectious marker in this postoperative setting. CD64 is a high-affinity receptor for the Fc portion of IgG. It is weakly expressed on the polynuclear neutrophils (PMNs) at rest [1, 2] but increases specifically after bacterial stimulation. Thus, CD64 analysis is proposed as an early infectious marker.

Methods

Prospective study realised in the medico-surgical ICU of CHU Charleroi (Belgium). Twenty-two patients (mean age 64 ± 13 years) scheduled for cardiac surgery were included in the analysis. The CD64 expression on neutrophils was quantified by the haematologic cell dyn sapphire method (Abott, USA). C-reactive protein, leukocyte count, white blood cells, platelets and temperature were also monitored. Values are expressed as median (25th to 75th) percentile.

Results

CD64 index (Figure 1) slightly rose from the day 0, median value 0.86 units (1.06 to 1.38 units) to day 5 after the surgery, 1.01 (1.32 to 1.68 units). However, this increase was moderate, and the median values did not exceed the usual threshold of 1.5 units. Conversely, CRP showed a large increase from normal values on day 0 to 8, 67 mg/dl (6.64 to 13.56 mg/dl) on day 5. No significant correlation (P > 0.05) was found between CD64 and the others parameters of inflammation (CRP, leukocyte count, PMNs, platelets and temperature).

Figure 1

Conclusions

Our results show that the neutrophil CD64 expression after cardiac surgery with ECC is only moderately increased. The role of this new biomarker in the early diagnosis of infection (after major surgery) should be assessed in prospective studies.