COMPARISON OF CD64 LEVELS PERFORMED BY THE FACS AND ACCELLIX SYSTEMS

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Immune therapy in sepsis: Are we ready to try again?

Immune therapy to ease the burden of sepsis has thus far failed to consistently improve patient outcomes. Advances in cancer immune therapy and awareness that prolonged immune-suppression in sepsis can leave patients vulnerable to secondary infection and death have driven resurgence in the field of sepsis immune-therapy investigation. As we develop and evaluate these novel therapies, we must learn from past experiences where single-mediator targeted immune therapies were blindly delivered to heterogeneous patient cohorts with complex and evolving immune responses. Advances in genomics, proteomics, metabolomics, and point-of-care technology, coupled with a better understanding of sepsis pathogenesis, have meant that personalised immune-therapy is on the horizon. Here, we review the complex immune pathogenesis in sepsis and the contemporary immune therapies that are being investigated to manipulate this response. An outline of the immune biomarkers that may be used to support this approach is also provided.

Advances in the understanding and treatment of sepsis-induced immunosuppression

Sepsis is defined as a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. Sepsis can induce acute kidney injury and multiple organ failures and represents the most common cause of death in the intensive care unit. Sepsis initiates a complex immune response that varies over time, with the concomitant occurrence of both pro-inflammatory and anti-inflammatory mechanisms. As a result, most patients with sepsis rapidly display signs of profound immunosuppression, which is associated with deleterious consequences. Scientific advances have highlighted the role of metabolic failure, epigenetic reprogramming, myeloid-derived suppressor cells, immature suppressive neutrophils and immune alterations in primary lymphoid organs (the thymus and bone marrow) in sepsis. An improved understanding of the mechanisms underlying this immunosuppression as well as of the similarities between sepsis-induced immunosuppression and immune defects in cancer or immunosenescence has led to novel therapeutic strategies aimed at stimulating immune function in patients with sepsis. Trials assessing the therapeutic benefit of IL-7, granulocyte-macrophage colony-stimulating factor (GM-CSF) and antibodies against programmed cell death protein 1 (PD1) and programmed cell death 1 ligand 1 (PDL1) for the treatment of sepsis are in progress. The reappraisal of sepsis pathophysiology has also resulted in a novel approach to the design of clinical trials evaluating sepsis treatments, based on an evaluation of the immune status and biomarker-based stratification of patients.