Neutrophil CD64 expression as a diagnostic marker for local infection and crystal-induced arthritis

Neutrophil CD64 Expression as a Diagnostic Marker in Patients Hospitalized with Exacerbations of COPD: A Prospective Observational Study

PURPOSE

The expression of the neutrophil high-affinity Fc-gamma receptor (CD64) can be used as a diagnostic marker for bacterial infection and sepsis. The aims of this study were to determine the diagnostic accuracy of CD64 compared to C-reactive protein (CRP) and white blood cell count (WBC) in patients hospitalized with acute exacerbations of COPD (AECOPD) and to investigate the kinetics of CD64 expression.

METHODS

The present study is a prospective, single-centre observation study. Blood samples were collected from patients hospitalized with AECOPD at admission and after 6, 24 and 48 h. Retrospective reviews on the patients' medical records were performed blinded to the CD64 results. The CD64 was measured using the Leuko64 kit from Trillium Diagnostics, LLC (Maine, USA) with the CELL-DYN Sapphire Haematology System (Abbott Laboratories, Illinois, USA). Diagnostic accuracy of the CD64, CRP and WBC was compared using a receiver operating characteristic (ROC) curve analysis.

RESULTS

A total of 113 patients were included. Thirty-six patients (32 %) had pulmonary infiltrate on chest X-ray at admission (PI). The CD64 was higher in samples from patients with AECOPD and PI than those without PI at admission (median 1.25 vs. 0.60, p = 0.002) and during 48 h of follow-up. The area under the ROC curve of CD64, CRP and WBC was 0.69, 0.73 and 0.64, respectively, (p = 0.42 for the test of difference).

CONCLUSION

Neutrophil CD64 expression has about the same diagnostic accuracy as CRP in diagnosing pneumonia in patients hospitalized with AECOPD, but does not add to the diagnostic accuracy of CRP and WBC count.

The assessment of neutrophil CD64 count as an early warning marker of joint replacement infection

120,000 hip and knee replacements are performed each year in the UK and more than 1 % of these require revision surgery due to infection. Current diagnostic tests used to diagnose infection of joint replacements, including the current gold standard C-reactive protein, which offers poor specificity when diagnosing infection in the post-operative period. In the post-operative period these tests are unable to differentiate between physiological inflammation and infection of the replacement. Early treatment through antibiotic and washout therapy is essential to eradicate infection, saving the patient and the NHS the stress of revision surgery, which offers a much poorer prognosis than the original operative procedure. Thus, a superior marker is required and CD64 has been proposed to fulfil the necessary requirements of an effective marker. Data from several studies utilising a flow cytometer support the view that CD64 is firstly, a good marker of systemic infection and secondly, when studied in conjunction with musculoskeletal infections alone, is a sensitive and specific marker of this type of infection. However, meta-analysis of studies in this field concludes that more highly powered studies are needed before definite conclusions can be drawn. Despite this, the studies do portray a strong case for CD64 being the future of diagnosis of post-operative infection.

CD64 as a potential biomarker in septic arthritis

Background

Traditional inflammatory markers are generally unhelpful in discerning septic arthritis from inflammatory joint disease due to their lack of specificity. We wished to explore the discriminatory power of the novel inflammatory marker, Fc-gamma-receptor type 1, CD64, in patients presenting with acute arthritis.

Methods

Patients were recruited prospectively in the time period June 2009 to December 2011. Thirty-six patients presenting with an acute flare of chronic rheumatic arthritis, 31 with crystal-induced arthritis and 23 with septic arthritis were included. Traditional inflammatory markers, CD64 and procalcitonin (PCT) were measured and their diagnostic abilities were compared.

Results

CD64 and PCT both demonstrated a specificity of 98%, but poor sensitivities of 59% and 52%, respectively. White blood cell count (WBC), and erythrocyte sedimentation rate (ESR) did not have significant discriminatory power, while C-reactive protein (CRP) proved to have the best diagnostic accuracy as measured by area under the ROC curve (AUC 0.92, 95% confidence-interval 0.87-0.98). Subgroup analysis excluding patients with septic arthritis without concurrent bacteremia, and likewise exclusion of the patients with septic arthritis caused by coagulase negative staphylococci, both improved the diagnostic accuracy of CD64 and PCT, but not of WBC and CRP.

Conclusions

CD64 and PCT are highly specific for infectious disease, but they predominantly measure bacteremia. Their use in hospital practice has yet to be defined, and especially so in localized infections.

Hypothermia induced by adenosine 5'-monophosphate attenuates early stage injury in an acute gouty arthritis rat model

To investigate whether the hypothermia induced by Adenosine 5'-Monophosphate (5'-AMP) could attenuate early stage injury in a rat acute gouty arthritis model. Ankle joint injection with monosodium urate monohydrate crystals (MSU crystals) in hypothermia rat model which was induced by 5'-AMP and then observe whether hypothermia induced by 5'-AMP could be effectively inhibit the inflammation on acute gouty arthritis in rats. AMP-induced hypothermia has protective effects on our acute gouty arthritis, which was demonstrated by the following criteria: (1) a significant reduction in the ankle swelling (p < 0.001); (2) a significant decrease in the occurrence of leukocyte infiltration and mild hemorrhage; (3) a significant reduction in the presence of serum Interleukin-1β (IL-1β, p < 0.001) and metalloproteinase-9 (MMP-9, p < 0.001); and (4) a significant inhibition in the Nuclear Factor -κappaB (NF-κB) activity (p < 0.001). AMP-induced hypothermia could inhibit acute inflammation reaction and protect the synovial tissue against acute injury in a rat acute gouty arthritis model.