Cell surface expression of FcγRI (CD64) on neutrophils and monocytes in patients with influenza A, with and without complications

Neutrophil CD64 index as a good biomarker for early diagnosis of bacterial infection in pregnant women during the flu season

Background

Pregnant women are at high risk of developing febrile illness during the flu season. Early identification of a viral or bacterial infection is crucial in the management of febrile pregnant patients. Neutrophil CD64 (nCD64) has been shown to have more important diagnostic value in sepsis than traditional inflammatory indicators.

Methods

The pregnant women enrolled were divided into three groups according to disease: influenza A infection, bacterial infection and healthy controls. Peripheral blood CD64, leukocyte, C-reactive protein (CRP), procalcitonin (PCT) and human Th1/Th2-related cytokines levels were routinely measured. The correlation between and diagnostic value of the nCD64 index and other biomarkers were evaluated using Spearman's correlation test and receiver operating characteristic (ROC) curve analysis.

Results

Pregnant women with bacterial infection had significantly elevated levels of leukocytes (8.4 vs. 5.95, 109/L; P = 0.004), CRP (89.70 vs. 50.05 mg/mL; P = 0.031), PCT (0.13 vs. 0.04 ng/mL; P = 0.010) and TNF-α (0.46 vs. 0.38 pg/mL; P = 0.012) and an elevated nCD64 index (12.16 vs. 0.81; P < 0.001) compared with those with influenza A infection. The area under the receiver operating characteristic (AUROC) curve of the nCD64 index to discriminate bacterial infection among pregnant women (AUROC = 0.9183, P < 0.0001) was the largest. The sensitivity and specificity of the nCD64 index at an optimal cut-off value of 3.16 were 84% and 100%, respectively, with a negative predictive value (NPV) of 94%.

Conclusions

Our study demonstrates the clinical value of the nCD64 index in distinguishing between bacterial infection and influenza A in pregnant women.

Point-of-care neutrophil CD64 as a rule in diagnostic test for bacterial infections in the emergency department

INTRODUCTION

Bacterial infections are frequently seen in the emergency department (ED), but can be difficult to distinguish from viral infections and some non-infectious diseases. Common biomarkers such as c-reactive protein (CRP) and white blood cell (WBC) counts fail to aid in the differential diagnosis. Neutrophil CD64 (nCD64), an IgG receptor, is suggested to be more specific for bacterial infections. This study investigated if nCD64 can distinguish bacterial infections from other infectious and non-infectious diseases in the ED.

METHODS

All COVID-19 suspected patients who visited the ED and for which a definitive diagnosis was made, were included. Blood was analyzed using an automated flow cytometer within 2 h after presentation. Patients were divided into a bacterial, viral, and non-infectious disease group. We determined the diagnostic value of nCD64 and compared this to those of CRP and WBC counts.

RESULTS

Of the 291 patients presented at the ED, 182 patients were included with a definitive diagnosis (bacterial infection n = 78; viral infection n = 64; non-infectious disease n = 40). ROC-curves were plotted, with AUCs of 0.71 [95%CI: 0.64-0.79], 0.77 [0.69-0.84] and 0.64 [0.55-0.73] for nCD64, WBC counts and CRP, respectively. In the bacterial group, nCD64 MFI was significantly higher compared to the other groups (p < 0.01). A cut-off of 9.4 AU MFI for nCD64 corresponded with a positive predictive value of 1.00 (sensitivity of 0.27, a specificity of 1.00, and an NPV of 0.64). Furthermore, a diagnostic algorithm was constructed which can serve as an example of what a future biomarker prediction model could look like.

CONCLUSION

For patients in the ED presenting with a suspected infection, nCD64 measured with automatic flow cytometry, has a high specificity and positive predictive value for diagnosing a bacterial infection. However, a low nCD64 cannot rule out a bacterial infection. For future purposes, nCD64 should be combined with additional tests to form an algorithm that adequately diagnoses infectious diseases.

High expression of neutrophil and monocyte CD64 with simultaneous lack of upregulation of adhesion receptors CD11b, CD162, CD15, CD65 on neutrophils in severe COVID-19

Background and Aims

The pronounced neutrophilia observed in patients with coronavirus disease 2019 (COVID-19) infections suggests a role for these leukocytes in the pathology of the disease. Monocyte and neutrophil expression of CD64 and CD11b have been reported as early biomarkers to detect infections. The aim of this study was to study the expression of receptors for IgG (CD64) and adhesion molecules (CD11b, CD15s, CD65, CD162, CD66b) on neutrophils and monocytes in patients with severe COVID-19 after admission to an intensive care unit (ICU).

Methods

The expression of receptors was analyzed using flow cytometry. EDTA blood from 23 patients with confirmed COVID-19 infection was sampled within 48 h of admission to the ICU. Leukocytes were labeled with antibodies to CD11b, CD15s, CD65s, CD162, CD64, and CD66b. Expression of receptors was reported as mean fluorescence intensity (MFI) or the percentage of cells expressing receptors.

Results

Results are presented as comparison of COVID-19 patients with the healthy group and the receptor expression as MFI. Neutrophil receptors CD64 (2.5 versus 0.5) and CD66b (44.5 versus 34) were increased and CD15 decreased (21.6 versus 28.3) when CD65 (6.6 versus 4.4), CD162 (21.3 versus 21.1) and CD11b (10.5 versus 12) were in the same range. Monocytes receptors CD64 (30.5 versus 16.6), CD11b (18.7 versus 9.8), and CD162 (38.6 versus 36.5) were increased and CD15 decreased (10.3 versus 17.9); CD65 were in the same range (2.3 versus 1.96).

Conclusion

Monocytes and neutrophils are activated during severe COVID-19 infection as shown by strong upregulation of CD64. High monocyte and neutrophil CD64 can be an indicator of a severe form of COVID19. The adhesion molecules (CD11b, CD162, CD65, and CD15) are not upregulated on otherwise activated neutrophils, which might lead to relative impairment of tissue migration. Low adhesion profile of neutrophils suggests immune dysfunction of neutrophils. Monocytes maintain upregulation of some adhesion molecules (CD11b, CD162) suggesting the persistence of an increased ability to migrate into tissues, even during a severe stage of COVID-19. Future research should focus on CD64 and CD11b kinetics in the context of prognosis.

Neutrophils in respiratory viral infections

Viral respiratory infections are a common cause of severe disease, especially in infants, people who are immunocompromised, and in the elderly. Neutrophils, an important innate immune cell, infiltrate the lungs rapidly after an inflammatory insult. The most well-characterized effector mechanisms by which neutrophils contribute to host defense are largely extracellular and the involvement of neutrophils in protection from numerous bacterial and fungal infections is well established. However, the role of neutrophils in responses to viruses, which replicate intracellularly, has been less studied. It remains unclear whether and, by which underlying immunological mechanisms, neutrophils contribute to viral control or confer protection against an intracellular pathogen. Furthermore, neutrophils need to be tightly regulated to avoid bystander damage to host tissues. This is especially relevant in the lung where damage to delicate alveolar structures can compromise gas exchange with life-threatening consequences. It is inherently less clear how neutrophils can contribute to host immunity to viruses without causing immunopathology and/or exacerbating disease severity. In this review, we summarize and discuss the current understanding of how neutrophils in the lung direct immune responses to viruses, control viral replication and spread, and cause pathology during respiratory viral infections.

Fc Gamma Receptors as Regulators of Bone Destruction in Inflammatory Arthritis

Bone erosion is one of the primary features of inflammatory arthritis and is caused by excessive differentiation and activation of osteoclasts. Fc gamma receptors (FcγRs) have been implicated in osteoclastogenesis. Our recent studies demonstrate that joint-deposited lupus IgG inhibited RANKL-induced osteoclastogenesis. FcγRI is required for RANKL-induced osteoclastogenesis and lupus IgG-induced signaling transduction. We reviewed the results of studies that analyzed the association between FcγRs and bone erosion in inflammatory arthritis. The analysis revealed the dual roles of FcγRs in bone destruction in inflammatory arthritis. Thus, IgG/FcγR signaling molecules may serve as potential therapeutic targets against bone erosion.

Diagnosis and Monitoring of Acute Infections with Emphasis on the Novel Biomarker Human Neutrophil Lipocalin

Background

Acute infections affect all of us at least once or twice a year. Sometimes the infection prompts a visit to our doctor, and the question asked by the patient and the doctor is whether the infection should be treated with antibiotics or not. This is an important question because unnecessary prescription of antibiotics adds to the increasing problem of antibiotics resistance. Objective means to determine whether the infection is caused by bacteria or virus, therefore, are necessary tools for the doctor.

Content

White blood cell counts, C-reactive protein, and other acute-phase reactants in blood are important tools and are commonly used, but unfortunately lack in sensitivity and specificity. In this review we describe some novel biomarkers with increased clinical performance in this regard. The superior biomarker is human neutrophil lipocalin (HNL), a protein released from activated blood neutrophils. HNL may be measured in serum, plasma, or in whole blood after activation with a neutrophil activator. The diagnostic accuracy in the distinction between bacterial and viral acute infections was shown to be in the range of 90%–95% when measured in serum or activated whole blood.

Summary

A point-of-care assay for the measurement of HNL in whole blood is currently being developed, which will allow the diagnosis of acute infections within 5–10 min. For certain indications, HNL measurement may be complemented by 1 or 2 other biomarkers, which may increase the diagnostic discrimination between bacterial and viral infections even further.

HNL (Human Neutrophil Lipocalin) and a multimarker approach to the distinction between bacterial and viral infections

OBJECTIVES

The distinction between bacterial and viral causes of acute infections is a major clinical challenge. In this report we investigate the diagnostic performance in this regard of nine candidate biomarkers together with HNL (Human Neutrophil Lipocalin).

METHODS

Blood was obtained from patients with symptoms of infectious (n = 581). HNL was measured in whole blood (B-HNL) after pre-activation with the neutrophil activator fMLP or in plasma (P-HNL). Azurocidin also known as heparin-binding protein (HBP), Calprotectin, PMN-CD64, CRP (C-reactive protein), IP-10 (Interferon γ-induced Protein 10 kDa), PCT (Procalcitonin), TK1 (Thymidine kinase 1), TRAIL (TNF-related apoptosis-inducing ligand) were measured in plasma/serum. Area under the ROC (receiver operating characteristics) curve (AuROC) was used for the evaluation of the clinical performance of the biomarkers.

RESULTS

Side-by-side comparisons of the ten biomarkers showed large difference in the AuROC with B-HNL being the superior biomarker (0.91, 95% CI 0.86-0.95) and with the other nine biomarkers varying from AuROC of 0.63-0.79. The combination of B-HNL with IP-10 and/or TRAIL increased the diagnostic performance further to AuROCs of 0.94-0.97. The AuROCs of the combination of CRP with IP-10 and/or TRAIL were significantly lower than combinations with B-HNL 0.87 (95% CI 0.83-0.91).

CONCLUSION

The diagnostic performance of whole blood activated HNL was superior in the distinction between bacterial or viral infections. The addition of IP-10 and/or TRAIL to the diagnostic algorithm increased the performance of B-HNL further. The rapid analysis of HNL, reflecting bacterial infections, together with biomarkers reflecting viral infections may be the ideal combination of diagnostic biomarkers of acute infections.

Peripheral neutrophil CD64 index combined with complement, CRP, WBC count and B cells improves the ability of diagnosing bacterial infection in SLE

OBJECTIVE

To investigate the diagnostic role of complement C3, complement C4, C-reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), neutrophil CD64 (nCD64) index, lymphocyte subsets and their combination in differentiating bacterial infection from disease relapse in systemic lupus erythematosus (SLE).

METHODS

The above biomarkers in 36 hospitalized SLE patients with bacterial infection and 45 with lupus flare without infection were retrospectively studied. Bacterial infection was proven by positive cultures or typical clinical symptoms and signs combined with positive response to antibiotics. Lupus flare was defined as three points greater than their previous SLE disease activity index score. The diagnostic value for bacterial infection was evaluated by the areas under the receiver operating characteristic curves (AUC) and a novel bioscore system combining multiple biomarkers.

RESULTS

Increased CRP ( p = 0.049), WBC ( p = 0.028) and nCD64 index ( p = 0.034) were observed in the infected group and C3 ( p = 0.001), C4 ( p = 0.016) and B cells levels ( p = 0.010) were significantly reduced. The AUC for the above six biomarkers had no significant difference. Interestingly, the combination of nCD64 index, CRP, WBC, C3 and C4 improved significantly the diagnostic potential of SLE infection (AUC 0.783 (interquartile range 0.672, 0.871), p < 0.001; sensitivity 85.29% specificity 62.50%). In the bioscore system including the above six biomarkers, the bacterial infection rate in patients with bioscore ≤2, 3, 4, 5 and 6 were 0.00, 39.29, 59.10, 61.54 and 100.00%, respectively.

CONCLUSION

The combination of nCD64 index, C3, C4, CRP, WBC and B cells in a bioscore is useful to diagnose bacterial infection in SLE.

CD64 on monocytes and granulocytes in severe acute bronchiolitis: Pilot study on its usefulness as a bacterial infection biomarker

The CD64 receptor has been described as a biomarker of bacterial infection. We speculated that CD64 surface expression on monocytes and granulocytes of children with severe acute bronchiolitis (SAB) could be altered in cases of probable bacterial infection (PBI) determined using classical biomarkers (procalcitonin and C-reactive protein, leukocyte count, and radiographic findings). A prospective observational pilot study was conducted from October 2015 to February 2016 in children admitted for pediatric critical care. A blood sample was taken in the first 24 hours of admission, and CD64 was measured by flow cytometry. The values obtained were analyzed and correlated with traditional biomarkers of PBI. Thirty-two children were included; a correlation was found between CD64 expression and the PBI criteria. CD64 surface expression was higher in children with PBI (area under the receiver operating characteristic curve of 0.73; P = 0.042) and the percentage of CD64⁺ granulocytes was higher in children with PBI. This is the first study to describe CD64 surface expression on monocytes and granulocytes in SAB, finding CD64 values to be higher in children with PBI. Larger clinical studies are needed to elucidate the real accuracy of CD64 as a biomarker of bacterial infection.

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.

Human Neutrophil Lipocalin as a Superior Diagnostic Means To Distinguish between Acute Bacterial and Viral Infections

The distinction between causes of acute infections is a major clinical challenge. Current biomarkers, however, are not sufficiently accurate. Human neutrophil lipocalin (HNL) concentrations in serum or whole blood activated by formyl-methionine-leucine-phenylalanine (fMLP) were shown to distinguish acute infections of bacterial or viral cause with high accuracy. The aim was therefore to compare the clinical performance of HNL with currently used biomarkers. Seven hundred twenty-five subjects (144 healthy controls and 581 patients with signs and symptoms of acute infections) were included in the study. C-reactive protein (CRP), the expression of CD64 on neutrophils, procalcitonin (PCT), and blood neutrophil counts were measured by established techniques, and HNL concentrations were measured in whole-blood samples after activation with fMLP. All tested biomarkers were elevated in bacterial as opposed to viral infections (P < 0.001). CRP, PCT, and CD64 expression in neutrophils was elevated in viral infections compared to healthy controls (P < 0.001). In the distinction between healthy controls and patients with bacterial infections, the areas under the receiver operating characteristic (ROC) curves were >0.85 for all biomarkers, whereas for the distinction between bacterial and viral infections, only HNL concentration in fMLP-activated whole blood showed an area under the ROC curve (AUROC) of >0.90 and superior clinical performance. The clinical performance of HNL in fMLP-activated whole blood was superior to current biomarkers and similar to previous results of HNL in serum. The procedure can be adopted for point-of-care testing with response times of <15 min.

Perioperative cytokine response to infection associated with elective arterial surgery

OBJECTIVE

The aim was to assess the cytokine response to acute inflammation and infection in vascular surgery.

DESIGN OF STUDY

Single-center, prospective cohort study.

METHODS

Blood samples from 96 consecutive patients undergoing elective vascular surgery were analyzed for C-reactive protein (CRP), total leukocyte counts (LPK), neutrophil CD64 expression, and cytokines using enzyme-linked immunosorbent assay.

RESULTS

Of the 25 investigated cytokines, 22 had lower postoperative mean values compared to preoperative values. Interleukin (IL) 6 (IL-6) was the only cytokine that increased significantly postoperatively. Combined analysis of CRP and CD64 together with IL-6 or IL-10 showed an individually unique association with postoperative infection (P < .05).

CONCLUSION

We have shown a positive correlation with perioperative infection for the proinflammatory cytokines and the anti-inflammatory cytokine IL-10 as well as a number of chemokines. To our knowledge, this is the first report linking IL-10 and chemokine plasma levels to perioperative infection in vascular surgery.

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.

A rapid flow cytometric method for distinguishing between febrile bacterial and viral infections

Antibiotic resistance due to the inappropriate use of antimicrobials is one of the most critical public health problems worldwide. A major factor underlying the unnecessary use of antibiotics is the lack of rapid and accurate diagnostic tests. Therefore, we aimed to develop a novel rapid flow cytometric method for distinguishing between febrile bacterial and viral infections. In this prospective comparative study, quantitative flow cytometric analysis of FcγRII/CD32, CR1/CD35, MHC Class I receptor (MHCI), and C5aR/CD88 on human phagocytes was performed in 286 hospitalized febrile patients with suspected infection. After using microbiological and serological detection methods, or clinical diagnosis, 205 patients were identified with either bacterial (n=136) or viral (n=69) infection. Receptor data from patients were compared to those of 50 healthy controls. We developed a flow cytometric marker of local and systemic bacterial infections designated "bacterial infection score (BIS)" incorporating the quantitative analysis of FcγRII/CD32, CR1/CD35, C5aR/CD88 and MHCI on neutrophils and/or monocytes, which displays 91% sensitivity and 92% specificity in distinguishing between microbiologically confirmed bacterial (n=77) and serologically confirmed viral infections (n=61) within 1h. The BIS method was effectively applied to distinguish between bacterial and viral (pandemic H1N1 influenza) pneumonia cases with 96% sensitivity and 92% specificity. We propose that the rapid BIS test can assist physicians in deciding whether antibiotic treatment is necessary, thus reducing unnecessary antimicrobial use.

Neutrophil CD64 (FcγRI) expression is a specific marker of bacterial infection: A study on the kinetics and the impact of major surgery

Neutrophil CD64 expression is a diagnostic marker for the early detection of bacterial infections. The aim was to investigate the kinetics of neutrophil CD64 expression during bacterial infection and the possible impact of surgical trauma. Blood samples were collected daily during 3 d after admission for analysis by flow cytometry of the surface expressions on neutrophils and monocytes of CD64, CD16, CD32, CD11b/CD18 and CD35, and analysis of serum CRP and blood WBC. Serum concentrations of IFNgamma, G-CSF, IL-6 and IL-8 were also analysed in adults. Eight children and 19 adult patients with bacterial infections, 12 patients admitted for hip-arthroplasty because of coxarthrosis and 30 healthy adults were studied. Neutrophil CD64 was increased all 3 d after start of treatment (p<0.0001) in children and adults with bacterial infections. The postoperative increase after surgery was less than the increase seen during bacterial infections (p<0.0001). CRP, G-CSF, IL-6 and IL-8 were raised both in bacterial infections and after surgery. Our results indicate that the expression of CD64 on neutrophils is a specific sign of bacterial infections. Neutrophil expression of CD64, therefore, seems to be a promising tool for the early detection of bacterial infections even during surgery.

Neutrophil and monocyte receptor expression in uncomplicated and complicated influenza A infection with pneumonia

Following influenza, the elderly and those with chronic heart/lung diseases are often affected by bacterial complications such as pneumonia. Whether neutrophil and monocyte functions are affected differently in patients with or without complications is less well known. Therefore, blood neutrophil and monocyte surface receptor expressions were measured in patients with influenza A, with or without complications, by means of flow cytometry. Neutrophil expressions of the adhesion molecules CD11b and CD66b were increased in influenza A, with the highest expression of CD11b in uncomplicated influenza. Monocyte expressions of CD11b and CD18 were also higher in influenza compared with bacterial infection and healthy controls. Neutrophil expressions of the phagocyte receptors CD64 and CD32 and the complement receptor CD35 were impaired in influenza with and without pneumonia compared with bacterial infection, whereas the expressions in monocytes were increased in all infected groups. The expression of the phagocyte receptor CD16 on neutrophils was impaired in all infected groups. Our results suggest increased recruitment of neutrophils and monocytes to infected areas by up-regulation of adhesion molecules in influenza that may be involved in the inflammatory response during infection. In contrast, depression of phagocyte receptor expression on neutrophils in patients with influenza pneumonia may contribute to increased susceptibility to bacterial infections and impaired clearance of encapsulated bacteria such as pneumococci.

Distinction between bacterial and viral infections

PURPOSE OF REVIEW

To commence proper treatment as rapidly as possible and to reduce unnecessary antibiotic treatments, timely knowledge of whether the infection is bacterial or viral in origin would be beneficial for the clinician. As a reliable prediction of the causative agent of bacterial infection is not possible based on clinical features, there is an ongoing need for sensitive and specific markers of bacterial infection.

RECENT FINDINGS

The most common differential diagnosis methods are reviewed here. It is also demonstrated that the measurement of the expression of complement receptors, particularly CR1 (CD35), on neutrophils can be a useful preliminary test to differentiate between bacterial and viral infections. In addition, a novel marker of local and systemic bacterial infections designated 'clinical infection score (CIS) point', which incorporates quantitative analysis of complement receptors on neutrophils and standard clinical laboratory data and displays 98% sensitivity and 97% specificity in distinguishing between bacterial and viral infections, is presented.

SUMMARY

We conclude that the diagnostic yield of measured individual variables in distinguishing between bacterial and viral infections increases upon combination.