Simultaneous quantitative analysis of the expression of CD64 and CD35 on neutrophils as markers to differentiate between bacterial and viral infections in patients with rheumatoid arthritis

Analysis of Risk Factors and Association of Cluster of Differentiation (CD) Markers With Conventional Markers in Delayed Fracture Related Infection for Closed Fracture

Background: Fracture-related infections (FRI) remain a difficult consequence for orthopedic trauma patients, their relatives, the treating physicians, and the healthcare systems. Delayed fracture-related infection is an important step in the infection process that can be controlled by diagnosing and preventing it from moving to the next level. Neutrophils CD64 and CD66b were identified as sensitive indicators in the event of infection. Normal sequential changes, on the other hand, occur after surgery and are extremely high. They are back to normal on the 10^th day after the operation. The aim of this study was, therefore, to examine the risk factors associated with fracture-related infection by comparing cluster of differentiation (CD) indicators with conventional markers and comparing them with gold standards culture reports. As a result, it could be an early sign of a closed fracture infection.

Material & Methods: Between February 2020 and March 2021, 510 patients from the Department of Orthopedics at King George Medical University in Lucknow agreed to participate in the study. The study included patients who had a closed fracture and had undergone elective or emergency surgery. Blood was withdrawn before the surgery (baseline) on day one and again on the third, seventh, and 10^th day after the operation to measure the quantitative measurements of the biomarkers (total leucocyte count [TLC], erythrocyte sedimentation rate [ESR], C reactive protein [CRP], CD64, and CD66b) in all follow-up examinations. Patients were monitored for delayed signs of the infection for 2 to 10 weeks. The biomarkers were evaluated and linked to the culture reports.

Results: Of the 510 patients included, 272 were men (53.3%) and 238 women (46.7%), the mean age was 40 (20-78), the mean age for fracture related infection with positive culture (FRI POS) was 48.0 (SD: 19.47), for fracture related infection with negative culture (FRI NEG) was 46.20 (SD: 17.18), and for patient with no signs of infections (NON-FRI) was 45.13 (SD: 17.62) (p <0.001), the mean duration of the fracture to admission (in hours) was 4.90 (SD: 1.92), 4.91 (SD: 2.65), and 5.14 (SD: 2.66) (p <0.001), respectively. The mean duration of admission to surgery (in hours) was 31.54 (SD: 85.14), 43.14 (SD: 105.64), and 61.84 (134.14), respectively (p <0.001). The mean duration of surgery was 4.63 (SD: 1.85), 5.14 (SD: 2.16), and 5.05 (SD: 2.16) (p <0.001). The risk factors such as bone type (p = 0.04) and addiction (p = 0.01) were identified as statistically significant. There was no correlation between the CD66b markers on the third, seventh, and 10^th days. CD64 was significantly correlated with ESR, TLC, and CRP on the 10^th day in the FRI-positive group (r = 0.638; p = 0.03) (r = 0.744; p = 0.009) (r = 0.817; p = 0.002).

Conclusion: The risk factors for infection in fracture patients are significantly influenced by the type of bone and addiction the patient is using. Elevated CD64 levels could be used as a diagnostic marker for infection early on the 10^th day after surgery before the appearance of clinical signs.

Comprehensive analysis of multiple cytokines and blood parameters for the diagnosis of bacterial infections in rheumatoid arthritis

Patients with rheumatoid arthritis (RA) are more susceptible to infections, which elevate the levels of relative cytokines. However, the ability of the cytokines levels to predicate bacterial infections in RA patients remains unclear. Here, we assessed the ability of the combination of serum cytokine levels and blood parameters to diagnose bacterial infections in RA patients. We measured the levels of a panel of serum cytokine and blood parameters in 168 RA patients and 81 healthy individuals. RA patients were divided into the bacterial infection (INFE) group (n = 76) and RA flare without INFE group (n = 92). Bacterial infection was confirmed by microbial culture, imaging, antibiotic response, and typical clinical symptoms. The discriminative ability of the combination of the cytokine levels and inflammatory parameters was assessed using the receiver-operating characteristic (ROC) curves analysis and a novel bioscore system. The levels of interleukin (IL)-6 (p = 0.006), IL-10 (p = 0.019), interferon (IFN)-γ (p = 0.033), CRP (p < 0.001), and ESR (p < 0.001) were higher in patients of the INFE group than in patients with RA flare, and the absolute numbers of CD19⁺ B cells (p < 0.001) and CD4⁺ T cells (p = 0.009) were lower. For discriminating bacterial infection, the combination of IL-6, IL-10, IFN-γ, ESR, CRP, CD19⁺ B cells, and CD4⁺ T cells, provided an area under the curve (AUC) of 0.827 [(95% confidence interval (CI): 0.760-0.881)], which was profoundly larger than that of IL-6, IL-10, IFN-γ, ESR, CRP, CD19⁺ B cells, or CD4⁺ T cells alone. In addition, we also developed a bioscore system based on the combination of these seven biomarkers. Seventeen (100%) patients with a bioscore of 0 were non-infected, while seven (100%) patients with a score of 7 had bacterial infections. The bioscore based on the combination of ESR, CRP, IL-6, IL-10, IFN-γ, CD19⁺ B cells and CD4⁺ T cells may be a promising and robust tool to diagnose bacterial infections in RA patients.

Flow cytometry evaluation of infection-related biomarkers in febrile subjects in the emergency department

Aim: In an Emergency Department (ED), the etiological identification of infected subjects is essential. 13 infection-related biomarkers were assessed using a new flow cytometry procedure. Materials & methods: If subjects presented with febrile symptoms at the ED, 13 biomarkers' levels, including CD64 on neutrophils (nCD64) and CD169 on monocytes (mCD169), were tested and compared with clinical records. Results: Among 50 subjects, 78% had bacterial infections and 8% had viral infections. nCD64 showed 82% sensitivity and 91% specificity for identifying subjects with bacterial infections. mCD169, HLA-ABC ratio and HLA-DR on monocytes had high values in subjects with viral infections. Conclusion: Biomarkers showed promising performances to improve the ED's infectious stratification.

Role of the interferons in CD64 and CD169 expressions in whole blood: Relevance in the balance between viral- or bacterial-oriented immune responses

Introduction

CD64 expression increases on neutrophils during bacterial infections. Recently an increase in CD169 expression has been discovered on monocytes during viral infections. Generally, interferons α (IFNsα) and IFNsγ are key drivers of the infectious host immune response. The purpose of this study was to explore if a link exists between these IFNs and both biomarkers.

Methods

Whole blood samples from healthy volunteers were stimulated with either IFNs, interleukins, or infectious extracts, to mimic an infectious state. Expressions of CD64 and CD169 were assessed in these samples by multiple flow cytometry methods, over precise kinetics.

Results

The expression of CD64 was statistically higher in samples stimulated with IFNγ, and CD169 in those stimulated with IFNα (and all other type I IFNs). Surface expressions are directly induced by their respective IFNs via Janus kinase/signal transducer and activator of transduction pathways within 6 to 8 hours of incubation. Mixing both types of IFNs seemed to indicate that they partially inhibit each other.

Conclusions

The induction of CD169 on monocytes and CD164 on neutrophils by type I and type II IFNs confirms the relevance of these markers for assessing between a viral‐ vs bacterial‐oriented immune response.

Clinical research assessment by flow cytometry of biomarkers for infectious stratification in an Emergency Department

Aim: Management of patients with infections within the Emergency Department (ED) is challenging for practitioners, as the identification of infectious causes remains difficult with current techniques. A new combination of two biomarkers was tested with a new rapid flow cytometry technique. Materials & methods: Subjects from the ED were tested for their CD64 on neutrophils (nCD64) and CD169 on monocytes (mCD169) levels and results were compared to their clinical records. Results: Among 139 patients, 29% had confirmed bacterial infections and 5% viral infections. nCD64 and mCD169 respectively showed 88 and 86% sensitivity and 90 and 100% specificity for identifying subjects in bacterial or viral conditions. Conclusion: This point-of-care technique could allow better management of patients in the ED.

Accuracy of neutrophil CD64 expression in diagnosing infection in patients with autoimmune diseases: a meta-analysis

We aimed to systematically evaluate the accuracy of nCD64 in diagnosing infection in patients with autoimmune diseases. Studies were searched in PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang, and Chongqing VIP databases up to October 2018. There was no restriction for language and age. Prospective studies examining the accuracy of nCD64 in diagnosing infection in patients with autoimmune diseases were included. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess the quality of eligible studies. Stata 15.1 and Meta-DiSc 1.4 software were used for data analysis. Eleven studies fulfilled the inclusion criteria (677 patients, 229 patients with bacterial infection, and 448 without infection). The pooled sensitivity and specificity of nCD64 were 89% (95% confidence interval (CI) 82-93) and 94% (95% CI 91-96), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 14.9 (95% CI 9.3-23.8) and 0.12 (95% CI 0.07-0.20), respectively. The diagnostic odds ratio and area under the summary receiver operating characteristic curve were 123 (95% CI 53-283) and 0.97 (95% CI 0.95-0.98), respectively. The univariate meta-regression analysis showed that region, type of disease, antibiotic therapy, and presentation of nCD64 measurement results were responsible for the heterogeneity. The Deeks' funnel plot asymmetry test showed that there was no publication bias (p = 0.15). nCD64 has a good overall diagnostic performance for differentiating infection from disease flare in patients with autoimmune diseases. Further studies are needed to confirm the optimized cutoff value.

Perioperative Increase in Neutrophil CD64 Expression is an Indicator for Intra-abdominal Infection after Colorectal Cancer Surgery

BACKGROUND

Colorectal surgery is associated with a high incidence of postoperative infections. Early clinical signs are difficult to distinguish from the systemic inflammatory response related to surgical trauma. Timely diagnosis may significantly improve the outcome. The objective of this study was to compare a new biomarker index CD64 for neutrophils (iCD64n) with standard biomarkers, white blood cell (WBC) count, neutrophil/lymphocyte ratio (NLR), C-reactive protein (CRP) and procalcitonin (PCT) for the early detection of postoperative infection.

METHODS

The prospective study included 200 consecutive patients with elective colorectal cancer surgery. Postoperative values of biomarkers from the postoperative day (POD) 1 to POD5 were analysed by the receiver operating characteristic (ROC) analysis to predict infection. The Cox regression model and the Kaplan-Meier method were used to assess prognostic factors and survival.

RESULTS

The increase of index CD64n (iCD64n) after surgery, expressed as the ratio iCD64n after/before surgery was a better predictor of infection than its absolute value. The best 30-day predictors of all infections were CRP on POD4 (AUC 0.72, 99% CI 0.61-0.83) and NLR on POD5 (AUC 0.69, 99% CI 0.57-0.80). The best 15-day predictors of organ/space surgical site infection (SSI) were the ratio iCD64n on POD1 (AUC 0.72, 99% CI 0.58-0.86), POD3 (AUC 0.73, 99% CI 0.59-0.87) and CRP on POD3 (AUC 0.72, 99% CI 0.57-0.86), POD4 (AUC 0.79, 99% CI 0.64-0.93). In a multivariate analysis independent risk factors for infections were duration of surgery and perioperative transfusion while the infection itself was identified as a risk factor for a worse long-term survival.

CONCLUSIONS

The ratio iCD64n on POD1 is the best early predictor of intra-abdominal infection after colorectal cancer surgery. CRP predicts the infection with the same predictive value on POD3.

Host Biomarkers for Distinguishing Bacterial from Non-Bacterial Causes of Acute Febrile Illness: A Comprehensive Review

Background

In resource limited settings acute febrile illnesses are often treated empirically due to a lack of reliable, rapid point-of-care diagnostics. This contributes to the indiscriminate use of antimicrobial drugs and poor treatment outcomes. The aim of this comprehensive review was to summarize the diagnostic performance of host biomarkers capable of differentiating bacterial from non-bacterial infections to guide the use of antibiotics.

Methods

Online databases of published literature were searched from January 2010 through April 2015. English language studies that evaluated the performance of one or more host biomarker in differentiating bacterial from non-bacterial infection in patients were included. Key information extracted included author information, study methods, population, pathogens, clinical information, and biomarker performance data. Study quality was assessed using a combination of validated criteria from the QUADAS and Lijmer checklists. Biomarkers were categorized as hematologic factors, inflammatory molecules, cytokines, cell surface or metabolic markers, other host biomarkers, host transcripts, clinical biometrics, and combinations of markers.

Findings

Of the 193 citations identified, 59 studies that evaluated over 112 host biomarkers were selected. Most studies involved patient populations from high-income countries, while 19% involved populations from low- and middle-income countries. The most frequently evaluated host biomarkers were C-reactive protein (61%), white blood cell count (44%) and procalcitonin (34%). Study quality scores ranged from 23.1% to 92.3%. There were 9 high performance host biomarkers or combinations, with sensitivity and specificity of ≥85% or either sensitivity or specificity was reported to be 100%. Five host biomarkers were considered weak markers as they lacked statistically significant performance in discriminating between bacterial and non-bacterial infections.

Discussion

This manuscript provides a summary of host biomarkers to differentiate bacterial from non-bacterial infections in patients with acute febrile illness. Findings provide a basis for prioritizing efforts for further research, assay development and eventual commercialization of rapid point-of-care tests to guide use of antimicrobials. This review also highlights gaps in current knowledge that should be addressed to further improve management of febrile patients.

Impact of T cell activation, HIV replication and hepatitis C virus infection on neutrophil CD64 expression

BACKGROUND

Overexpression of the Fc receptor CD64 on neutrophils is associated with innate immune response and bacterial infections. During HIV infection a large set of immune disorders including T-lymphocyte over-activation, microbial translocation, impairment of neutrophil functions, and immunodeficiency may interplay with neutrophil CD64 expression.

METHODS

Associations of neutrophil CD64 expression with CD8⁺ T cell activation, CD4⁺ T cells number, HIV, and HCV replications were investigated in HIV infected patients using a standardized method.

RESULTS

Higher neutrophil CD64 expression was observed in HIV infected subjects compared to healthy controls (0.91 vs. 0.75, P < 0.001). Among 115 HIV infected patients, nine (8.8%) had a CD64 expression over the clinical threshold as calculated against bead standard (i.e., 1.5). HIV viremic patients were more likely to have an index above 1.5 (OR: 6.68, P values: 0.01). A trend for correlation between CD64 expression and CD8 T cell activation was observed (P values: 0.08). Blood CD4⁺ T lymphocyte depletion and HCV replication did not affect neutrophil CD64 expression.

CONCLUSIONS

HIV infection and HIV replication are associated with up-regulation of neutrophil CD64. CD64 overexpression above the clinical threshold was observed in a minor proportion of HIV infected individuals treated by antiretroviral therapy and may be a marker of neutrophil activation related to non-AIDS-linked comorbidities. © 2016 International Clinical Cytometry Society.

Utility of immune response-derived biomarkers in the differential diagnosis of inflammatory disorders

Differentiating between inflammatory disorders is difficult, but important for a rational use of antimicrobial agents. Biomarkers reflecting the host immune response may offer an attractive strategy to predict the etiology of an inflammatory process and can thus be of help in decision making. We performed a review of the literature to evaluate the diagnostic value of inflammatory biomarkers in adult patients admitted to the hospital with suspected systemic acute infections. Elevated procalcitonin (PCT) concentrations indicate a bacterial infection in febrile patients with an auto-immune disease, rather than a disease flare. CD64 expression on neutrophils can discriminate between non-infectious systemic inflammation and sepsis, and limited evidence suggests the same for decoy receptor 3. PCT is useful for both diagnosing bacterial infection complicating influenza and guiding antibiotic treatment in lower respiratory tract infections in general. In undifferentiated illnesses, increased CD35 expression on neutrophils distinguishes bacterial from viral infections. Compared to bacterial infections, invasive fungal infections are characterized by low concentrations of PCT. No biomarker predicting a specific infecting agent could be identified.

Neutrophil CD64 level as a rapid and promising diagnostic tool for infectious diseases in elderly patients

AIM

We examined the utility of the neutrophil CD64 level as a rapid and sensitive diagnostic marker for infections in febrile aged patients.

METHODS

The expression level of CD64 per neutrophil was quantitatively measured with flow cytometry using a QuantiBrite kit in samples from febrile (aged >65 years) patients. Information about the presence or absence of infectious disease was retrospectively obtained from each patient's medical record in which attending physicians were obliged to write down a tentative diagnosis after resolution of manifestations.

RESULTS

With receiver operating characteristic curve evaluation using the results, a CD64 level >2000 molecules per neutrophil was sensitive and specific for detecting infection. Among 102 patients suspected of having infection, 72 patients were diagnosed with infectious diseases, and 30 patients had non-infectious diseases. The sensitivity and specificity of determination of the neutrophil CD64 level were 88% and 63%, respectively. However, considering the high frequency of infections in elderly patients (71% in the present study), the post-test probability reached as high as 93%. The positive likelihood ratio was 2.4, and the negative likelihood ratio was 0.2.

CONCLUSIONS

Considering the frequency of infectious diseases in elderly patients, determination of the neutrophil CD64 level helps detect infectious diseases.

Combined use of biomarkers for distinguishing between bacterial and viral etiologies in pediatric lower respiratory tract infections

BACKGROUND

In clinical practice it is often troublesome to discriminate bacterial etiologies from viral etiologies in pediatric lower respiratory tract infections (LRTIs). The aim of this study was to develop an accurate analytic method to improve diagnostic determination for bacterial and viral etiologies in pediatric LRTIs.

METHODS

A total of 45 children with confirmed bacterial LRTIs and 51 children with viral LRTIs were finally included after assessment of the children visiting the emergency department with a suspected infection and identification of pathogens. C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), CD35, and CD64 were assessed and then the areas under receiver operating characteristic (ROC) curves (AUC) of PCT, IL-6, CD35, and CD64 in combination with CRP were compared to the AUC of CRP alone in all subjects.

RESULTS

The levels of CRP, PCT, IL-6, CD45, and CD64 observed in children with bacterial LRTIs were statistically higher than for viral infections. The AUC of CRP combined with CD53 (0.963, 95% confidence interval (CI) 0.921-1.002) or CD64 (0.952, 95% CI 0.907-0.998) or CD35/CD64 (0.971, 95% CI 0.932-1.004) increased compared with that of the single biomarker.

CONCLUSIONS

The combined analysis improved diagnostic accuracy in children with bacterial and viral LRTIs.

Quantitative flow cytometric analysis of expression of tumor necrosis factor receptor types I and II on mononuclear cells

BACKGROUND

Tumor necrosis factor (TNF)-α is an inflammatory cytokine, the biological effects of which are mediated by the interaction with specific membrane-bound receptors. To assess TNF-α receptor (TNFR) expression, it is important to estimate both the number of cells that carry these receptors and the number of receptors per cell, because the cell fate depends on the balance between TNFRI and TNFRII signaling.

OBJECTIVE

The aim of the present study was to develop an optimized protocol to estimate the level of expression of membrane-bound TNFRI and TNFRII, using QuantiBRITE PE calibration beads.

MATERIALS AND METHODS

The percentage of cells that expressed membrane-bound TNFRI and TNFRII and the mean number of receptors per cell were determined by flow cytometry using PE-labeled antibodies against TNFR. To create a calibration curve and convert cell fluorescence intensity values to absolute numbers of receptors, we used QuantiBRITE PE beads.

RESULTS

CD19(+) B lymphocytes had the least percentage of cells expressing TNFRI and the greatest number of receptor molecules per cell, whereas CD3(+) T lymphocytes had the greatest percentage of cells expressing TNFRII and the lowest density of these receptors. We also established that stimulation of peripheral blood mononuclear cells (PBMCs) with the lipopolysaccharide (LPS) significantly increased the number of TNFRI and TNFRII on CD14(+) monocytes.

CONCLUSION

Application of the protocol-identified differences in the percentage of cells that expressed TNFRs, as well as the absolute number of receptors per cell, among different subpopulations of PBMCs, and between PBMCs cultured with and without LPS.

Neutrophil CD64 expression as a biomarker in the early diagnosis of bacterial infection: a meta-analysis

BACKGROUND

Neutrophil CD64 expression is widely reported as an efficacious biomarker to differentiate infected patients from other non-infected patients. This meta-analysis was conducted to comprehensively and quantitatively summarize the accuracy of neutrophil CD64 in the early diagnosis of bacterial infection.

METHODS

A systematic review of related studies was conducted, and the sensitivity, specificity, and other data about the accuracy of CD64 expression on neutrophils were pooled using random effects models with 95% confidence intervals (CI) as the effect measurements. Summary receiver operating characteristic (SROC) curves and the Q* value were also calculated in the meta-analysis. Heterogeneity was tested, as well as the publication bias. Potential sources of heterogeneity were explored by assessing whether or not certain covariates significantly influenced the summary diagnostic odds ratio (SDOR).

RESULTS

A total of 26 studies including 3944 patients met the inclusion criteria for the final analysis. The summary estimate was 0.76 (95% CI 0.74-0.78) for sensitivity and 0.85 (95% CI 0.83-0.86) for specificity. The positive likelihood ratio (PLR), negative likelihood ratio (NLR), SDOR, and area under the SROC of neutrophil CD64 expression with Q* value were 6.67 (95% CI 4.67-9.53), 0.24 (95% CI 0.18-0.31), 34.29 (95% CI 19.59-60.01), and 0.92 (Q*=0.85), respectively. The pooled data from the included studies had high heterogeneity and the Egger test suggested a publication bias.

CONCLUSIONS

On the basis of our meta-analysis, neutrophil CD64 expression could be a promising and meaningful biomarker for diagnosing bacterial infection. Nevertheless, more large prospective studies should be carried out before the neutrophil CD64 test is used widely in the clinical setting because of the various cut-off values.