Simultaneous quantitative analysis of FcgammaRI (CD64) expression on neutrophils and monocytes: a new, improved way to detect infections

Point-of-care neutrophil and monocyte surface markers differentiate bacterial from viral infections at the emergency department within 30 min

Rapid discrimination between viral and bacterial infections in a point-of-care setting will improve clinical outcome. Expression of CD64 on neutrophils (neuCD64) increases during bacterial infections, whereas expression of CD169 on classical monocytes (cmCD169) increases during viral infections. The diagnostic value of automated point-of-care neuCD64 and cmCD169 analysis was assessed for detecting bacterial and viral infections at the emergency department. Additionally, their value as input for machine learning models was studied. A prospective observational cohort study in patients suspected of infection was performed at an emergency department. A fully automated point-of-care flow cytometer measured neuCD64, cmCD169, and additional leukocyte surface markers. Flow cytometry data were gated using the FlowSOM algorithm. Bacterial and viral infections were assessed in standardized clinical care. The sole and combined diagnostic value of the markers was investigated. Clustering based on unsupervised machine learning identified unique patient clusters. Eighty-six patients were included. Thirty-five had a bacterial infection, 30 had a viral infection, and 21 had no infection. neuCD64 was increased in bacterial infections (P < 0.001), with an area under the receiver operating characteristic curve (AUROC) of 0.73. cmCD169 was higher in virally infected patients (P < 0.001; AUROC 0.79). Multivariate analyses incorporating additional markers increased the AUROC for bacterial and viral infections to 0.86 and 0.93, respectively. The additional clustering identified 4 distinctive patient clusters based on infection type and outcome. Automated neuCD64 and cmCD169 determination can discriminate between bacterial and viral infections. These markers can be determined within 30 min, allowing fast infection diagnostics in the acute clinical setting.

Combined CD25, CD64, and CD69 Biomarker in 3D-Printed Multizone Millifluidic Device for Sepsis Detection in Clinical Samples

Sepsis is a serious medical condition that arises from a runaway response to an infection, which triggers the immune system to release chemicals into the bloodstream. This immune response can result in widespread inflammation throughout the body, which may cause harm to vital organs and, in more severe cases, lead to organ failure and death. Timely and accurate diagnosis of sepsis remains a challenge in analytical diagnostics. In this work, we have developed and validated a sepsis detection device, utilizing 3D printing technology, which incorporates multiple affinity separation zones. Our device requires minimal operator intervention and utilizes CD64, CD69, and CD25 as the biomarker targets for detecting sepsis in liquid biopsies. We assessed the effectiveness of our 3D-printed multizone cell separation device by testing it on clinical samples obtained from both septic patients (n = 35) and healthy volunteers (n = 8) and validated its performance accordingly. Unlike previous devices using poly(dimethyl siloxane), the 3D-printed device had reduced nonspecific binding for anti-CD25 capture, allowing this biomarker to be assayed for the first time in cell separations. Our results showed a statistically significant difference in cell capture between septic and healthy samples (with p values of 0.0001 for CD64, CD69, and CD25), suggesting that 3D-printed multizone cell capture is a reliable method for distinguishing sepsis. A receiver operator characteristic (ROC) analysis was performed to determine the accuracy of the captured cell counts for each antigen in detecting sepsis. The ROC area under the curve (AUC) values for on-chip detection of CD64+, CD69+, and CD25+ leukocytes were 0.96, 0.92, and 0.88, respectively, indicating our diagnostic test matches clinical outcomes. When combined for sepsis diagnosis, the AUC value for CD64, CD69, and CD25 was 0.99, indicating an improved diagnostic performance due to the use of multiple biomarkers.

The wild mouse bone marrow has a unique myeloid and lymphoid composition and phenotype

The murine bone marrow has a central role in immune function and health as the primary source of leukocytes in adult mice. Laboratory mice provide a human-homologous, genetically manipulable and reproducible model that has enabled an immeasurable volume of high-quality immunological research. However, recent research has questioned the translatability of laboratory mouse research into humans and proposed that the exposure of mice to their wild and natural environment may hold the key to further immunological breakthroughs. To date, there have been no studies providing an in-depth cellular analysis of the wild mouse bone marrow. This study utilized wild mice from an isolated island population (Isle of May, Scotland, UK) and performed flow cytometric and histological analysis to characterize the myeloid, lymphoid, hematopoietic progenitor, and adipocyte compartments within the wild mouse bone marrow. We find that, compared to laboratory mouse bone marrow, the wild mouse bone marrow differs in every cell type assessed. Some of the major distinctions include; a smaller B cell compartment with an enriched presence of plasma cells, increased proportions of KLRG1+ CD8+ T cells, diminished CD11b expression in the myeloid lineage and a five-fold enlargement of the eosinophil compartment. We conclude that the wild mouse bone marrow is dramatically distinct from its laboratory counterparts, with multiple phenotypes that to our knowledge have never been observed in laboratory models. Further research into these unique features may uncover novel immunological mechanisms and grant a greater understanding of the role of the immune system in a natural setting.

Diagnosis of Neonatal Sepsis: The Role of Inflammatory Markers

This is a narrative review on the role of biomarkers in the diagnosis of neonatal sepsis. We describe the difficulties to obtain standardized definitions in neonatal sepsis and discuss the limitations of published evidence of cut-off values and their sensitivities and specificities. Maternal risk factors influence the results of inflammatory markers as do gestational age, the time of sampling, the use of either cord blood or neonatal peripheral blood, and some non-infectious causes. Current evidence suggests that the use of promising diagnostic markers such as CD11b, CD64, IL-6, IL-8, PCT, and CRP, either alone or in combination, might enable clinicians discontinuing antibiotics confidently within 24-48 h. However, none of the current diagnostic markers is sensitive and specific enough to support the decision of withholding antibiotic treatment without considering clinical findings. It therefore seems to be justified that antibiotics are often initiated in ill term and especially preterm infants. Early markers like IL-6 and later markers like CRP are helpful in the diagnosis of neonatal sepsis considering the clinical aspect of the neonate, the gestational age, maternal risk factors and the time (age of the neonate regarding early-onset sepsis) of blood sampling.

Immunomonitoring of Monocyte and Neutrophil Function in Critically Ill Patients: From Sepsis and/or Trauma to COVID-19

Immune cells and mediators play a crucial role in the critical care setting but are understudied. This review explores the concept of sepsis and/or injury-induced immunosuppression and immuno-inflammatory response in COVID-19 and reiterates the need for more accurate functional immunomonitoring of monocyte and neutrophil function in these critically ill patients. in addition, the feasibility of circulating and cell-surface immune biomarkers as predictors of infection and/or outcome in critically ill patients is explored. It is clear that, for critically ill, one size does not fit all and that immune phenotyping of critically ill patients may allow the development of a more personalized approach with tailored immunotherapy for the specific patient. In addition, at this point in time, caution is advised regarding the quality of evidence of some COVID-19 studies in the literature.

Rapid detection of bacterial infection using a novel single-tube, four-colour flow cytometric method: Comparison with PCT and CRP

BACKGROUND

A key factor behind the unnecessary use of antibiotics is the lack of rapid and accurate diagnostic tests. In this study, we developed a novel and fast flow cytometric single-tube method to detect bacterial infections within 30 minutes.

METHODS

Quantitative flow cytometric four-colour analysis of host biomarkers CD35, CD64, CD329, and MHC class I expression on neutrophils and lymphocytes was performed on samples taken from 841 febrile patients with suspected infection. Obtained data was incorporated into the four-colour bacterial infection (FCBI)-index, using the developed bacterial infection algorithm.

FINDINGS

In distinguishing between microbiologically confirmed bacterial (n = 193) and viral (n = 291) infections, the FCBI-index method was superior to serum C-reactive protein (CRP) and procalcitonin (PCT). In 269 confirmed viral respiratory tract infections, 43% (95% CI: 37-49%) of the patients had an increased FCBI-index, suggesting probable bacterial coinfection.

INTERPRETATION

The proposed FCBI-index test might be a potent additional tool when assessing appropriateness of empiric antibiotic treatment.

FUNDING

This study has been financially supported by Turku University Hospital (Turku, Finland) and The Finnish Medical Foundation.

High sPLA2-IIA level is associated with eicosanoid metabolism in patients with bacterial sepsis syndrome

The aim of this study was to determine the association between secretory phospholipase A2 group IIA (sPLA2-IIA) and eicosanoid pathway metabolites in patients with bacterial sepsis syndrome (BSS). Levels of sPLA2-IIA, eicosanoids prostaglandin (PG)E2, PGD synthase were quantified in the sera from patients confirmed to have bacterial sepsis (BS; N = 45), bacterial severe sepsis/septic shock (BSS/SS; N = 35) and healthy subjects (N = 45). Cyclooxygenase (COX)-1 and COX-2 activities were analyzed from cell lysate. Serum levels of sPLA2-IIA, PGE2, and PGDS increased significantly in patients with BS and BSS/SS compared to healthy subjects (p<0.05). COX-2 activity was significantly increased in patients with BS compared to healthy subjects (p<0.05), but not COX-1 activity. Binary logistic regression analysis showed that sPLA2-IIA and PGE2 were independent factors predicting BSS severity. In conclusion, high level of sPLA2-IIA is associated with eicosanoid metabolism in patients with BSS.

The diagnostic roles of neutrophil in bloodstream infections

Bloodstream infections remain a leading cause of death worldwide, despite advances in critical care and understanding of the pathophysiology and treatment strategies. No specific biomarkers or therapy are available for these conditions. Neutrophils play a critical role in controlling infection and it is suggested that their migration and antimicrobial activity are impaired during sepsis which contribute to the dysregulation of immune responses. Recent studies further demonstrated that interruption or reversal of the impaired migration and antimicrobial function of neutrophils improves the outcome of sepsis in animal models. In this review, we provide an overview of the associated diagnostic biomarkers involved neutrophils in sepsis, and discuss the potential of neutrophils as a target to specifically predict the outcome of sepsis.

CD35 and CD64 of Neutrophils Can Differentiate Between Bacterial and Viral Infections in Children by Simultaneous Quantitative Analysis

BACKGROUND The aim of this study was to determine the relationship between the expression of CD35 and CD64 from white blood cells (neutrophil, monocytes, and lymphocytes) and acute infectious diseases in children. MATERIAL AND METHODS The blood samples were collected from 104 children with infections (42 viral infections and 62 bacterial infections). Blood samples were stained with CD45-PC5, CD35-FITC, and CD64-PE, and the fluorescence intensities were measured by flow cytometer, and then the ratio of CD35 to CD64 was calculated. RESULTS The ratio of CD64/CD35 on neutrophils (NCD35/NCD64) was significantly different between the bacterial group, the virus group, and the healthy control group. According to receiver operating characteristic (ROC) analysis, a cutoff value of 7.256 (sensitivity: 90.0%, specificity: 93.7%) was determined for the NCD35/NCD64 ratio. CONCLUSIONS This study shows that NCD35/NCD64 is helpful in the differential diagnosis of acute viral infection and bacterial infection in children.

Children With Noncritical Infections Have Increased Intestinal Permeability, Endotoxemia and Altered Innate Immune Responses

BACKGROUND

Children with critical illness have increased intestinal permeability and a period of immunoparalysis, mediated by elevated circulating endotoxin. Whether children with less severe infections have similar changes is uncertain.

METHODS

We conducted a proof-of-concept pilot study, enrolling children 6-59 months of age hospitalized for noncritical infections (cases, n = 11) and noninfected controls (n = 19). Intestinal permeability was measured by lactulose-mannitol recovery. Plasma endotoxin, blood monocyte and neutrophil immunophenotypes and cytokine elaboration following 24-hour whole-blood culture with antigens targeting distinct innate pathogen recognition receptor signaling pathways were evaluated.

RESULTS

Cases had higher intestinal permeability and plasma endotoxin levels than controls. Among cases versus controls, fewer monocytes expressed human leukocyte antigen DR isotype (HLA-DR) (87.1% vs. 96.4%, P = 0.001), and more expressed CD64 (99.6% vs. 97.6%, P = 0.041). Following zymosan stimulation of whole blood, cases versus controls produced less interleukin 1 beta (IL-1β) (median 1101 vs. 2604 pg/mL, P = 0.048) and tumor necrosis factor alpha (TNF-α) (2342 vs. 5130 pg/mL, P = 0.031). Children with higher (≥0.1 endotoxin unit (EU)/mL) versus lower (<0.1 EU/mL) circulating endotoxin had fewer monocytes expressing CD86 (69.8% vs. 92.4%, P = 0.003) and less expression of CD64 following 24-hour zymosan stimulation (median fluorescence intensity (MFI) 1514 vs. 2196, P = 0.022).

CONCLUSIONS

Children hospitalized with noncritical infections had increased intestinal permeability, endotoxemia and altered monocyte phenotype and function. Collectively, these changes are typical of immunoparalysis seen in children with critical illness and may increase the risk of subsequent infections.

Can biomarkers improve the rational use of antibiotics?

PURPOSE OF REVIEW

We aim to review recent literature about the use of biomarkers to guide the initiation and duration of antibiotic treatments for suspected bacterial infections.

RECENT FINDINGS

Several good quality meta-analyses show that procalcitonin can be safely used to guide antibiotic-related decisions, especially for respiratory infections, thereby decreasing unnecessary antibiotic exposure. Furthermore, the use of CRP-based algorithms to guide antibiotic initiation in primary care patients with acute respiratory infections is associated with a reduction in antibiotic use without an increase in adverse events. Regarding neutrophil CD64 and serum amyloid A, more good-quality evidence is needed to assess their utility as biomarkers to tailor antibiotic use. Finally, transcriptomics, metabolomics and proteomics are promising tools for the development of tests to differentiate specific host responses to viral, bacterial and noninfectious stimuli, but such tests still need further validation.

SUMMARY

Evidence shows that the use of biomarkers, procalcitonin and CRP, can safely reduce unnecessary antibiotic prescriptions in certain infectious syndromes. The clinical utility of host-based strategies such as transcriptomics, metabolomics and proteomics for the diagnosis of infectious diseases has yet to be evaluated, as well as considerations such as costs, technical complexity and result turnaround time.

Utility of leucocyte antigens in distinguishing between bacterial and viral infection in children

Introduction

Accurate diagnosis of bacterial and viral infection is very difficult. Unfortunately, there is still no quick and discriminative diagnostic test that would help clinicians in establishing the diagnosis and taking a decision on treatment. The aim of the study was to compare the expression of antigens on phagocytes, which are involved in the first defence line during bacterial and viral infections in children, as a potential tool to distinguish the etiology of the infection.

Material and methods

The expression of CD35, CD32, CD88, and MHC class I on phagocytes in 49 blood samples from children with high fever and suspected infection as well as 19 healthy children (control group) was assessed by flow cytometry. Thirty-three children were diagnosed with bacterial and 16 with viral infection. Expression of antigens was analysed on a FACSCanto II flow cytometer according to mean fluorescence intensity (MFI) and antibody binding cites (ABC).

Results

Significant differences were observed for the following: CD32, CD35, CD88, and MHCI on granulocytes; CD32, CD35, CD88 on monocytes; and MHC-I ratio between groups were observed. The obtained results did not allow us to establish valuable score points for distinguishing between bacterial and viral infections. Classification and a regression tree using CD88 expression on granulocytes and CRP was developed. It enabled us to differentiate between the origin of infection with sensitivity and specificity of more than 90%.

Conclusions

Utility of use of wide range antigens’ expression on phagocytes for distinguishing between bacterial and viral infection in children has limited value. More adequate seems to be use of CD88 expression on granulocytes linked with CRP value.

An Amperometric Biosensor for the Determination of Bacterial Sepsis Biomarker, Secretory Phospholipase Group 2-IIA Using a Tri-Enzyme System

A tri-enzyme system consisting of choline kinase/choline oxidase/horseradish peroxidase was used in the rapid and specific determination of the biomarker for bacterial sepsis infection, secretory phospholipase Group 2-IIA (sPLA2-IIA). These enzymes were individually immobilized onto the acrylic microspheres via succinimide groups for the preparation of an electrochemical biosensor. The reaction of sPLA2-IIA with its substrate initiated a cascading enzymatic reaction in the tri-enzyme system that led to the final production of hydrogen peroxide, which presence was indicated by the redox characteristics of potassium ferricyanide, K₃Fe(CN)₆. An amperometric biosensor based on enzyme conjugated acrylic microspheres and gold nanoparticles composite coated onto a carbon-paste screen printed electrode (SPE) was fabricated and the current measurement was performed at a low potential of 0.20 V. This enzymatic biosensor gave a linear range 0.01–100 ng/mL (R² = 0.98304) with a detection limit recorded at 5 × 10⁻³ ng/mL towards sPLA2-IIA. Moreover, the biosensor showed good reproducibility (relative standard deviation (RSD) of 3.04% (n = 5). The biosensor response was reliable up to 25 days of storage at 4 °C. Analysis of human serum samples for sPLA2-IIA indicated that the biosensor has potential for rapid bacterial sepsis diagnosis in hospital emergency department.

Time Course of CD64, a Leukocyte Activation Marker, During Cardiopulmonary Bypass Surgery

Distinction between inflammation secondary to surgery, especially coronary artery bypass graft with cardiopulmonary bypass (CPB), and inflammation due to infection is difficult in surgical intensive care unit (ICU) patients. Development of biomarkers of infection could help clinicians in the early identification and thus treatment of sepsis in these patients. We compared the time course of the neutrophil CD64 index, a high affinity immunoglobulin FC γ receptor I whose expression is increased in bacterial infection, in 39 patients undergoing cardiac surgery with CPB and 11 patients admitted to the ICU with severe sepsis or septic shock. The CD64 index was significantly more elevated in septic patients than in patients who had CPB except at day 5. The CD64 index increased moderately on day 1 after cardiac surgery but the value remained lower than in septic patients. The duration for which the CD64 index was greater than 1.0 was longer in septic than in CPB patients. Receiver operating curves to differentiate CPB from sepsis on day 1 were not significantly different between C-reactive protein (CRP) concentrations and CD 64 index. Nevertheless, combination of low CD64 index with low CRP concentrations on day 1 ruled out sepsis except in three patients. There were no correlations between the CD64 index and cytokine levels (tumor necrosis factor [TNF]-α, interferon [IFN]γ, interleukin [IL]-6, IL-10, IL-8, IL-12) measured in subpopulations. In conclusion, CD64 index only in combination with CRP concentrations could be used to discriminate inflammation due to surgery from that due to infection in this particular population.

Detection of sepsis in patient blood samples using CD64 expression in a microfluidic cell separation device

A microfluidic affinity separation device was developed for the detection of sepsis in critical care patients.

Rivaroxaban attenuates thrombosis by targeting the NF-κB signaling pathway in a rat model of deep venous thrombus

Anticoagulant therapy is commonly used for the prevention and treatment of patients with deep venous thrombus. Evidence has shown that rivaroxaban is a potential oral anticoagulant drug for the acute treatment of venous thromboembolism. However, the rivaroxaban-mediated molecular mechanism involved in the progression of deep venous thrombosis has not been investigated. In the present study, we investigated the efficacy of rivaroxaban and the underlying signaling pathways in the prevention and treatment of rats with deep venous thrombosis. A rat model with deep vein thrombus formation was established and received treatment with rivaroxaban or PBS as control. The thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor-1 (PAI-1) were analyzed both in vitro and in vivo. The progression of thrombosis and stroke was evaluated after treatment with rivaroxaban or PBS. Nuclear factor-κB (NF-κB) signaling pathway in venous endothelial cells and in the rat model of deep venous thrombus was assessed. The therapeutic effects of rivaroxaban were evaluated as determined by changes in deep venous thrombosis in the rat model. Our results showed that rivaroxaban markedly inhibited TAFI and PAI-1 expression levels, neutrophils, tissue factor, neutrophil extracellular traps (NETs), myeloperoxidase and macrophages in venous endothelial cells and in the rat model of deep venous thrombus. Expression levels of ADP, PAIs, von Willebrand factor (vWF) and thromboxane were downregulated in vein endothelial cells and in serum from the experimental rats. Importantly, the incidences of inferior vena cava filter thrombus were protected by rivaroxaban during heparin-induced thrombolysis deep venous thrombosis in the rat model. We observed that activity of the NF-κB signaling pathway was inhibited by rivaroxaban in vein endothelial cells both in vitro and in vivo. Notably, immunohistology indicated that rivaroxaban attenuated deep venous thrombosis and the accumulation of inflammatory factors in the lesions in venous thrombus. Matrix metalloproteinase (MMP) expression and activity were downregulated in rivaroxaban-treated rats with deep venous thrombus. Rivaroxaban inhibited the elasticity of the extracellular matrix and collagen-elastin fibers. On the whole, these results indicate that rivaroxaban attenuates deep venous thrombus through MMP-9-mediated NF-κB signaling pathway.

Alteration in Leukocyte Subsets and Expressions of FcγR and Complement Receptors among Female Ragpickers in Eastern India

Background

There are a million ragpickers in India who gather and trade recyclable municipal solid wastes materials for a living. The objective of this study was to examine whether their occupation adversely affects their immunity.

Methods

Seventy-four women ragpickers (median age, 30 years) and 65 age-matched control housemaids were enrolled. Flow cytometry was used to measure leukocyte subsets, and leukocyte expressions of Fcγ receptor I (CD64), FcγRIII (CD16), complement receptor 1 (CD35) and CR3 (CD11b/CD18), and CD14. Serum total immunoglobulin-E was estimated with enzyme-linked immunosorbent assay.

Results

Compared with the controls, ragpickers had significantly (p < 0.0001) higher levels of CD8+T-cytotoxic, CD16+CD56+natural killer, and CD4+CD45RO+memory T-cells, but depleted levels of CD19+B-cells. The percentage of CD4+T-helper-cells was lower than the control group (p < 0.0001), but their absolute number was relatively unchanged (p = 0.42) due to 11% higher lymphocyte counts in ragpickers. In ragpickers, the percentages of CD14+CD16+intermediate and CD14dim CD16+nonclassical monocyte subsets were elevated with a decline in CD14+CD16-classical monocytes. The expressions of CD64, CD16, CD35, and CD11b/CD18 on both monocytes and neutrophils, and CD14 on monocytes were significantly higher in ragpickers. In addition, ragpickers had 2.7-times more serum immunoglobulin-E than the controls (p < 0.0001). After controlling potential confounders, the profession of ragpicking was positively associated with the changes.

Conclusion

Ragpicking is associated with alterations in both innate (neutrophils, monocytes, and natural killer cell numbers and expression of complement and Fcγ receptors) and adaptive immunity (numbers of circulating B cells, helper, cytotoxic, and memory T cells).

Low-level arsenic causes chronic inflammation and suppresses expression of phagocytic receptors

The impact of chronic low-level groundwater arsenic (As) exposure [in the range above the WHO-recommended limit of 10 μg/L but ≤50 μg/L (permissible limit of As for many Asian countries)] was investigated for cross talk of inflammatory changes and expression of phagocytic receptors of exposed rural women (N, 45) from districts of 24 Parganas (south) and in matched control groups (N, 43) [As ≤10 μg/L] from the same district. Systemic inflammation was evident from the upregulated levels of pro-inflammatory mediators like tumor necrosis factor-α (TNF-α); interleukins (ILs) like IL-6, IL-8, and IL-12; and C-reactive protein (CRP) in the sera and upregulated expression of protein kinase B phosphorylated at ser473 (pAKTser473)/nuclear factor-κB (NF-κB)/TNF-α axis in the leukocytes of exposed women with respect to control. We found that low-dose As exposure apart from inflicting inflammation altered the expression of phagocytic receptors-Fcγ receptors (FcγRs) and complement receptors (CRs). The leukocytes of the low-As-exposed women exhibited suppression of CD64, CD35, and CD11b and increased expression of CD16 with respect to control. Groundwater As showed a negative correlation with CD64 expression on monocytes [Pearson's r, -0.8205; 95% confidence interval (CI), -0.8789 to -0.7379] and granulocytes [r, -0.7635; 95% CI, -0.8388 to -0.6595] and a positive correlation with CD16 on granulocytes [r, 0.8363; 95% CI, 0.7599 to 0.8899]. A negative correlation of groundwater As was also observed with expression of CD35 on granulocytes [r, -0.8780; 95% CI, -0.9185 to -0.8192] and monocytes [r, -0.7778; 95% CI, -0.8490 to -0.6790] and CD11b on monocytes [r, -0.6035; 95% CI, -0.7218 to -0.4511]. Therefore, it may be indicated that chronic low-level As exposure (11-50 μg/L) not only evoked chronic inflammatory changes but also suppressed the expression of FcγRs and CRs in the exposed women. This, in turn, may lead to susceptibility towards pathogenic infections or in long run may even contribute towards chronic inflammatory diseases including cancer.

The Expression Level of Neutrophil CD64 Is a Useful Marker of Systemic Inflammation Associated with HIV Infection

CD64 is an Fc-gamma-receptor type 1. The expression level of neutrophil CD64 (nCD64) is a known bacterial infection marker, and it also increases in viral infections. We examined the absolute nCD64 before and after the initiation of antiretroviral therapy (ART) to determine its role as an infection and inflammation marker of human immunodeficiency virus (HIV) infection. In this prospective observational study, 94 HIV-infected patients were enrolled and classified into ART (n = 62), ART naive (n = 24), and acute/early phase groups (n = 8). The median nCD64 was 1,430 molecules/cell in the ART group, 2,994 in the ART naive group, 4,625 in the acute/early phase group, and 1,196 in the healthy control group. The nCD64 in the ART group was significantly higher compared with the healthy controls (p = .041), and the nCD64 in the ART naive and acute/early phase groups was significantly higher compared with the ART group (both p < .001). In the ART naive group, nCD64 was significantly higher in patients with than without concomitant infections (3,942 ± 1,519 vs. 2,300 ± 784, p = .004). However, this was influenced by the fact that nCD64 elevated as the stage of HIV infection progressed. nCD64 decreased significantly during the 24 weeks after starting ART (p = .004), although an upward trend in nCD64 was observed at weeks 2 and 4, without symptoms. When immune reconstitution inflammatory syndrome occurred, nCD64 elevated with a wider range than did C-reactive protein. This preliminary study suggests that nCD64 would be useful as a marker of the systemic inflammation of HIV-infected patients.

Maturation-associated gene expression profiles along normal human bone marrow monopoiesis

Human monopoiesis is a tightly coordinated process which starts in the bone marrow (BM) haematopoietic stem cell (HSC) compartment and leads to the production of circulating blood mature monocytes. Although mature monocytes/macrophages have been extensively studied in both normal or inflammatory conditions, monopoiesis has only been assessed in vitro and in vivo animal models, due to low frequency of the monocytic precursors in the normal human BM. Here we investigated the transcriptional profile along normal human BM monopoiesis. Five distinct maturation-associated stages of monocytic precursors were identified and isolated from (fresh) normal human BM through fluorescence-activated cell sorting, and the gene expression profile (GEP) of each monocytic precursor subset was analysed by DNA-oligonucleotide microarrays. Overall, >6000 genes (18% of the genes investigated) were expressed in ≥1 stage of BM monopoiesis at stable or variable amounts, showing early decrease in cell proliferation with increased levels of expression of genes linked with cell differentiation. The here-defined GEP of normal human BM monopoiesis might contribute to better understand monocytic differentiation and the identification of novel monocytic candidate markers, while also providing a frame of reference for the study of monocytic maturation in both neoplastic and non-neoplastic disease conditions involving monocytic precursor cells.

CD64 and Group II Secretory Phospholipase A2 (sPLA2-IIA) as Biomarkers for Distinguishing Adult Sepsis and Bacterial Infections in the Emergency Department

INTRODUCTION

Early diagnosis of sepsis and bacterial infection is imperative as treatment relies on early antibiotic administration. There is a need to develop new biomarkers to detect patients with sepsis and bacterial infection as early as possible, thereby enabling prompt antibiotic treatment and improving the survival rate.

METHODS

Fifty-one adult patients with suspected bacterial sepsis on admission to the Emergency Department (ED) of a teaching hospital were included into the study. All relevant cultures and serology tests were performed. Serum levels for Group II Secretory Phospholipase A2 (sPLA2-IIA) and CD64 were subsequently analyzed.

RESULTS AND DISCUSSION

Sepsis was confirmed in 42 patients from a total of 51 recruited subjects. Twenty-one patients had culture-confirmed bacterial infections. Both biomarkers were shown to be good in distinguishing sepsis from non-sepsis groups. CD64 and sPLA2-IIA also demonstrated a strong correlation with early sepsis diagnosis in adults. The area under the curve (AUC) of both Receiver Operating Characteristic curves showed that sPLA2-IIA was better than CD64 (AUC = 0.93, 95% confidence interval (CI) = 0.83-0.97 and AUC = 0.88, 95% CI = 0.82-0.99, respectively). The optimum cutoff value was 2.13μg/l for sPLA2-IIA (sensitivity = 91%, specificity = 78%) and 45 antigen bound cell (abc) for CD64 (sensitivity = 81%, specificity = 89%). In diagnosing bacterial infections, sPLA2-IIA showed superiority over CD64 (AUC = 0.97, 95% CI = 0.85-0.96, and AUC = 0.95, 95% CI = 0.93-1.00, respectively). The optimum cutoff value for bacterial infection was 5.63μg/l for sPLA2-IIA (sensitivity = 94%, specificity = 94%) and 46abc for CD64 (sensitivity = 94%, specificity = 83%).

CONCLUSIONS

sPLA2-IIA showed superior performance in sepsis and bacterial infection diagnosis compared to CD64. sPLA2-IIA appears to be an excellent biomarker for sepsis screening and for diagnosing bacterial infections, whereas CD64 could be used for screening bacterial infections. Both biomarkers either alone or in combination with other markers may assist in decision making for early antimicrobial administration. We recommend incorporating sPLA2-IIA and CD64 into the diagnostic algorithm of sepsis in ED.

Determination of CD64 for the Diagnosis of Bacterial Chronic Prostatitis

PROBLEM

CD64 is a 72-kDa transmembrane glycoprotein, the highest affinity receptor of immunoglobulin (IgG), and a member of the IgG superfamily. The CD64 expression by leukocytes in the prostatic fluid was determined by flow cytometry to explore the clinical significance of this glycoprotein in the diagnosis of chronic prostatitis (CP).

METHOD OF STUDY

Prostatic fluid samples collected from 116 CP patients and 27 normal cases were subjected to bacterial culture and leukocyte CD64 expression determination using flow cytometry with monoclonal antibodies.

RESULTS

The leukocyte CD64 expression levels of the pathogen groups were significantly higher than those of the normal groups, especially those of Staphylococcus simulans (3879.26 ± 764.52/cell) and Staphylococcus auricularis (2903.14 ± 137.61/cell). The leukocyte CD64 expression in the prostatic fluid was more rapidly and accurately detected by flow cytometry than by bacterial culture.

CONCLUSIONS

CD64 expression by leukocytes in the prostatic fluid correlated with bacterial infection and may serve as a marker for the early diagnosis of CP.

Diagnostic utility of neutrophil CD64 as a marker for early-onset sepsis in preterm neonates

Introduction

Neutrophil CD64 has been proposed as an early marker of sepsis. This study aims to evaluate the diagnostic utility of neutrophil CD64 for identification of early-onset sepsis in preterm neonates.

Methods

The prospective study was conducted in a neonatal intensive care unit between November 2010 and June 2011. Preterm neonates in whom infection was suspected when they were <12 hours of age were enrolled. Complete blood count with differential, blood culture, neutrophil CD11b and CD64 measurement were performed. Receiver operating characteristic curve analysis was performed to evaluate the performance of neutrophil CD64 as biomarker of sepsis.

Results

A total of 158 preterm neonates was enrolled, 88 of whom were suspected infection. The suspected sepsis group was of lesser gestational age (P<0.001) and lower birth weight (P<0.001), compared with controls. The hematologic profiles of the suspected sepsis group were characterized by higher white blood cell count, neutrophil counts and C-reactive protein. The suspected sepsis neonates had significantly higher neutrophil CD64 expression compared with controls. Neutrophil CD64 had an area value under the curve of 0.869 with an optimal cutoff values of 1010 phycoerythrin molecules bound/cell and it had a high sensitivity (81.82%) and negative predictive value (77.4%). The level of neutrophil CD64 was independent of antibiotic therapy within 24 hours after the onset of sepsis in preterm neonates.

Conclusions

Neutrophil CD64 is a highly sensitive marker for suspected early-onset sepsis in preterm neonates. Our study suggests that neutrophil CD64 may be incorporated as a valuable marker to diagnose infection.

Analysis of autofluorescence in polymorphonuclear neutrophils: a new tool for early infection diagnosis

Diagnosing bacterial infection (BI) remains a challenge for the attending physician. An ex vivo infection model based on human fixed polymorphonuclear neutrophils (PMNs) gives an autofluorescence signal that differs significantly between stimulated and unstimulated cells. We took advantage of this property for use in an in vivo pneumonia mouse model and in patients hospitalized with bacterial pneumonia. A 2-fold decrease was observed in autofluorescence intensity for cytospined PMNs from broncho-alveolar lavage (BAL) in the pneumonia mouse model and a 2.7-fold decrease was observed in patients with pneumonia when compared with control mice or patients without pneumonia, respectively. This optical method provided an autofluorescence mean intensity cut-off, allowing for easy diagnosis of BI. Originally set up on a confocal microscope, the assay was also effective using a standard epifluorescence microscope. Assessing the autofluorescence of PMNs provides a fast, simple, cheap and reliable method optimizing the efficiency and the time needed for early diagnosis of severe infections. Rationalized therapeutic decisions supported by the results from this method can improve the outcome of patients suspected of having an infection.

Sepsis: multiple abnormalities, heterogeneous responses, and evolving understanding

Sepsis represents the host's systemic inflammatory response to a severe infection. It causes substantial human morbidity resulting in hundreds of thousands of deaths each year. Despite decades of intense research, the basic mechanisms still remain elusive. In either experimental animal models of sepsis or human patients, there are substantial physiological changes, many of which may result in subsequent organ injury. Variations in age, gender, and medical comorbidities including diabetes and renal failure create additional complexity that influence the outcomes in septic patients. Specific system-based alterations, such as the coagulopathy observed in sepsis, offer both potential insight and possible therapeutic targets. Intracellular stress induces changes in the endoplasmic reticulum yielding misfolded proteins that contribute to the underlying pathophysiological changes. With these multiple changes it is difficult to precisely classify an individual's response in sepsis as proinflammatory or immunosuppressed. This heterogeneity also may explain why most therapeutic interventions have not improved survival. Given the complexity of sepsis, biomarkers and mathematical models offer potential guidance once they have been carefully validated. This review discusses each of these important factors to provide a framework for understanding the complex and current challenges of managing the septic patient. Clinical trial failures and the therapeutic interventions that have proven successful are also discussed.

Diagnostic accuracy of lipopolysaccharide-binding protein for predicting bacteremia/clinical sepsis in children with febrile neutropenia: comparison with interleukin-6, procalcitonin, and C-reactive protein

PURPOSE

In febrile neutropenia (FN), no reliable marker has been identified to discriminate between severe infection and other causes of fever early in the clinical course. Since lipopolysaccharide-binding protein (LBP) has proven to be an accurate biomarker of bacteremia/clinical sepsis in critically ill non-immunocompromised infants and children, we performed a prospective study to determine the diagnostic accuracy of LBP in children with FN.

METHODS

Concentrations of LBP, procalcitonin (PCT), interleukin-6 (IL-6), and C-reactive protein (CRP) were prospectively measured on two consecutive days in 90 FN episodes experienced by 47 children. Receiver operating characteristic curve analysis was performed for each biomarker to predict bacteremia/clinical sepsis and severe sepsis.

RESULTS

Eighteen of the 90 episodes were classified as bacteremia/clinical sepsis. On both days 1 and 2, all biomarkers had a low to intermediate diagnostic accuracy for sepsis, and no significant differences were found between them (area under the curve (AUC) for LBP, 0.648 and 0.714; for PCT, 0.665 and 0.744; for IL-6, 0.775 and 0.775; and for CRP, 0.695 and 0.828). Comparison of their AUCs to the AUC of maximum body temperature on admission (AUC = 0.668) also failed to show any significant differences. In severe sepsis, however, the best diagnostic accuracies were found for IL-6 and PCT (AUC 0.892 and 0.752, respectively), and these were significantly higher than those for LBP (AUC 0.566) on admission.

CONCLUSIONS

On admission and 24 h later, the LBP concentration is less accurate for predicting bacteremia/clinical sepsis compared to IL-6, PCT, and CRP.

Polymorphic mononuclear neutrophils CD64 index for diagnosis of sepsis in postoperative surgical patients and critically ill patients

BACKGROUND

Surface neutrophil CD64 expression is upregulated in patients with bacterial infection. As it was suggested that the CD64 index could be used to detect sepsis in hospitalized patients, we questioned whether the CD64 index could discriminate between septic patients and postoperative surgical patients, defined as systemic inflammatory response syndrome (SIRS), both admitted at the intensive care unit (ICU). Furthermore, we wondered whether the CD64 index was an improved diagnostic compared to standard assays used at the laboratory. For this, outclinic (OC) patients were included as controls.

METHODS

The Leuko64™ assay was used to determine the CD64 index in residual EDTA blood samples from selected septic patients (n=25), SIRS patients (n=19), and OC patients (n=24). Additionally, WBC count, neutrophilic and eosinophilic granulocyte count, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured simultaneously.

RESULTS

The CD64 index was higher in septic patients compared to both the SIRS and OC group (p<0.0001). In addition, the WBC count, neutrophil count, ESR and CRP were also higher in septic patients than the OC group (p<0.0001). However, only the WBC count, eosinopenia, and ESR were comparable between the SIRS and the sepsis group and proved to be discriminative to the OC group (p<0.05). The CD64 index demonstrated higher sensitivity and specificity than CRP, WBC count, neutrophilic and eosinophilic granulocyte count, and ESR.

CONCLUSIONS

A high CD64 index was found in septic intensive care patients, while a low CD64 index was observed in OC and SIRS patients, demonstrating that the CD64 index can be used for routine diagnostics in the ICU setting.

Use of complement regulators, CD35, CD46, CD55, and CD59, on leukocytes as markers for diagnosis of viral and bacterial infections

Several complement regulatory proteins exist on self-cells to prevent damage by the serum complement system. In the present study, we aimed to perform quantitative analysis of membrane-bound complement regulators, CR1 (CD35), MCP (CD46), DAF (CD55), and MIRL (CD59), on peripheral blood neutrophils, monocytes, and lymphocytes from healthy controls (n=36) and febrile patients diagnosed with either bacterial (n=21) or viral (n=26) infections. Our results show that: (a) increased CD35 and CD55 levels on neutrophils and monocytes present potent markers of bacterial infection, (b) increased expression of CD46 on monocytes is an indicator of viral infection, and (c) increased CD59 expression on neutrophils and monocytes is a general infection marker. Additionally, CD19-positive B-lymphocytes represent practically the only lymphocyte population capable of expressing CD35. We further developed two novel clinical flow cytometric markers (indices), specifically, clinical mononucleosis (CM)-INDEX (incorporating CD35, CD55, and CD59 expression on lymphocytes) and clinical bacterial infection (CBI)-INDEX (incorporating CD35 and CD55 expression on neutrophils and lymphocytes), for the effective detection of viral mononucleosis and bacterial infection, respectively. In summary, bacterial and viral infections induce different expression patterns of membrane-bound complement regulators in human leukocytes, which may be effectively exploited in clinical differential diagnosis.

Evaluation of CD64 expression on neutrophils as an early indicator of neonatal sepsis

BACKGROUND

Enhanced neutrophil CD64 (nCD64) expression is likely to be useful in diagnosis of neonatal sepsis. This study evaluated the diagnostic efficacy of nCD64 expression as an early indicator of neonatal sepsis.

METHODS

Sixty neonates (culture positive, 24; negative, 36) with suspected sepsis and 30 controls were studied prospectively. CD64 expression was evaluated flow cytometrically on neutrophils and monocytes. Mean and median nCD64 expression, mean and median monocyte CD64/nCD64 (M/N CD64) ratios were computed. Results were correlated with blood culture and other conventional indices of sepsis.

RESULTS

The sick neonates had significantly higher mean and median nCD64 expression compared with controls. Monocyte CD64 values did not differ significantly among the groups. Both mean and median M/N CD64 ratios were significantly lower in the former group. Culture-positive neonates had significantly higher mean and median nCD64 values and significantly lower mean and median M/N CD64 ratios than clinically indistinguishable but culture-negative neonates. Both groups were significantly different with respect to these indices from normal controls. Median M/N CD64 ratio was the best discriminant by virtue of highest area under the receiver operator characteristic curve (0.903), with sensitivity and specificity of 91.7% and 88.9%, respectively. Conventional indices were inferior, both singly and in combination.

CONCLUSIONS

Enhanced nCD64 reported as median M/N CD64 ratio is a highly sensitive marker of culture-positive neonatal sepsis. It additionally identifies a separate group among culture-negative sick neonates and may be useful to guide antibiotic administration especially in these neonates.

New perspectives for natural antimicrobial peptides: application as antinflammatory drugs in a murine model

Background

Antimicrobial peptides (AMPs) are an ancient group of defense molecules. AMPs are widely distributed in nature (being present in mammals, birds, amphibians, insects, plants, and microorganisms). They display bactericidal as well as immunomodulatory properties. The aim of this study was to investigate the antimicrobial and anti-inflammatory activities of a combination of two AMPs (temporin B and the royal jellein I) against Staphylococcus epidermidis.

Results

The temporin B (TB-KK) and the royal jelleins I, II, III chemically modified at the C terminal (RJI-C, RJII-C, RJIII-C), were tested for their activity against 10 different Staphylococcus epidermidis strains, alone and in combination. Of the three royal jelleins, RJI-C showed the highest activity. Moreover, the combination of RJI-C and TB-KK (MIX) displayed synergistic activity. In vitro, the MIX displayed low hemolytic activity, no NO₂^- production and the ability to curb the synthesis of the pro-inflammatory cytokines TNF-α and IFN-γ to the same extent as acetylsalicylic acid. In vivo, the MIX sterilized mice infected with Staphylococcus epidermidis in eleven days and inhibited the expression of genes encoding the prostaglandin-endoperoxide synthase 2 (COX-2) and CD64, two important parameters of inflammation.

Conclusion

The study shows that the MIX – a combination of two naturally occurring peptides - displays both antimicrobial and anti-inflammatory activities.

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 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.

Bacterial infections, DNA virus infections, and RNA virus infections manifest differently in neutrophil receptor expression

Treating viral illnesses or noninfective causes of inflammation with antibiotics is ineffective and contributes to the development of antibiotic resistance, toxicity, and allergic reactions, leading to increasing medical costs. A major factor behind unnecessary use of antibiotics is, of course, incorrect diagnosis. For this reason, timely and accurate information on whether the infection is bacterial in origin would be highly beneficial. In this paper we will present our recent studies on the expression of opsonin receptors on phagocytes. The analysis of the expression levels of FcγRI, CR1, and CR3, along with CRP and ESR data, provides a novel application to the diagnosis of infectious and inflammatory diseases. The best clinical benefit will be obtained when the individual variables are combined to generate the CIS point method for a bacterial infection marker, DNAVS point for differentiating between DNA and RNA virus infections, and CRP/CD11b ratio for a marker of Gram-positive sepsis.

Early diagnosis of sepsis using serum biomarkers

Sepsis, an innate immunological response of systemic inflammation to infection, is a growing problem worldwide with a relatively high mortality rate. Immediate treatment is required, necessitating quick, early and accurate diagnosis. Rapid molecular-based tests have been developed to address this need, but still suffer some disadvantages. The most commonly studied biomarkers of sepsis are reviewed for their current uses and diagnostic accuracies, including C-reactive protein, procalcitonin, serum amyloid A, mannan and IFN-γ-inducible protein 10, as well as other potentially useful biomarkers. A singular ideal biomarker has not yet been identified; an alternative approach is to shift research focus to determine the diagnostic relevancy of multiple biomarkers when used in concert. Challenges facing biomarker research, including lack of methodology standardization and assays with better detection limits, are discussed. The ongoing efforts in the development of a multiplex point-of-care testing kit, enabling quick and reliable detection of serum biomarkers, may have great potential for early diagnosis of sepsis.

Evaluation of adhesion molecules CD64, CD11b and CD62L in neutrophils and monocytes of peripheral blood for early diagnosis of neonatal infection

BACKGROUND

This study was undertaken to assess the value of neutrophils CD11b, CD64, and CD62L for the early diagnosis of neonatal infection.

METHODS

Eighty-four neonates who were followed up for a suspected neonatal infection were included in this study. They were assigned into an infection group (n=49) and a non-infection group (n=35). Healthy neonates served as controls (n=35). A full sepsis screening was performed and neutrophil and monocyte expressions of CD11b, CD64 and CD62L were determined by flow cytometry.

RESULTS

The expressions of CD64 and CD11b were significantly enhanced in the infection group compared to the non-infective group and the controls.

CONCLUSIONS

CD64 expression on neutrophils and monocytes is a useful diagnostic marker for the early diagnosis of neonatal infection. Combination of CD64, CD11b and C reactive protein further enhances the sensitivity of the expression and its negative predictive value.

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

OBJECTIVES

The expression level of CD64 on neutrophils can be used to differentiate between an infection and a disease flare in rheumatoid arthritis (RA) patients. However, the CD64 expression is elevated by both bacteria and viruses, so it cannot be used to distinguish the type of infection. We herein investigated the results of a simultaneous quantitative analysis of the expression of CD64 and CD35 on neutrophils to determine whether these molecules can be used to distinguish between bacterial and viral infections in RA patients.

METHODS

We collected blood from 22 RA patients with pathogen-proven infections (15 bacterial and 7 viral infections). Blood samples were stained with QuantiBRITE CD64PE/CD45PerCP and CD35PE, and the mean fluorescence intensities were assessed by a flow cytometer. The mean numbers of molecules were calculated using QuantiBrite PE beads.

RESULTS

We calculated the ratio of CD64 to the CD35 level (CD35/CD64), and used a cut-off value of 2.8 for the CD35/CD64 ratio. At this value, the sensitivity for diagnosing a bacterial infection was 87%, and the specificity was 86%.

CONCLUSIONS

Simultaneous quantitative analysis of CD64 and CD35 expression on neutrophils might be useful to distinguish between bacterial and viral infections in RA patients.

Clinical review: flow cytometry perspectives in the ICU - from diagnosis of infection to monitoring of injury-induced immune dysfunctions

Septic syndromes represent a major healthcare problem worldwide. Clinical and experimental evidence indicates that septic patients rapidly present with numerous compromised immune functions. Although flow cytometry remains a relatively confidential diagnostic tool, it could be useful at every step of ICU patient management. Indeed, neutrophil CD64 expression is a sensitive and specific tool for diagnosis of sepsis in adults, neonates and children. Diminished monocyte HLA-DR expression is a reliable marker for the development of monocyte anergy, prediction of secondary nosocomial infection and death in critically ill patients. Finally, the measurement of an increased CD4⁺CD25⁺CD127^low regulatory T-cell percentage may represent a reliable marker for the diagnosis of lymphocyte dysfunctions in these patients. Ideally, these biomarkers should be part of a panel helping to define ICU patients' immune status. The potential of flow cytometry is further illustrated by use of the biomarkers listed above as stratification tools in preliminary clinical studies. Importantly, many other markers of immune dysfunctions are currently under development that could further enable the administration of targeted individualized therapy in ICU patients. The next critical step would be to use these standardized flow cytometry protocols in large multicentric clinical trials testing individualized immunotherapy.

Comparison of Fcγ receptor expression on neutrophils with procalcitonin for the diagnosis of sepsis in critically ill patients

BACKGROUND AND OBJECTIVE

The expression of Fc receptors for IgG (FcγRs) on neutrophils, including CD16, CD32 and CD64, may be modulated in response to sepsis. We investigated the expression of FcγRs on neutrophils and procalcitonin (PCT) as biomarkers of sepsis among critically ill patients.

METHODS

This prospective study was conducted in a 24-bed respiratory intensive care unit between July 2007 and June 2008. Critically ill patients requiring mechanical ventilation were enrolled and categorized into three groups: those with systemic inflammatory response syndrome (SIRS), those with severe sepsis and those with septic shock. Expression of FcγRs on neutrophils was quantitatively measured by flow cytometry immediately after enrolment of the patient. Serum PCT levels were also measured. Receiver operating characteristic (ROC) curves were used to evaluate the performance of FcγR expression and PCT as biomarkers of sepsis.

RESULTS

Sixty-six patients were enrolled, including 11 with SIRS, 31 with severe sepsis and 24 with septic shock. Nineteen healthy volunteers served as normal controls. CD64 was upregulated, CD16 was downregulated and CD32 remained unchanged during sepsis. CD64 expression and the ratio of CD64/CD16 increased significantly with the severity of sepsis. However, serum PCT levels were not significantly different between SIRS and severe sepsis patients. CD64, CD64/CD16 and PCT all significantly predicted sepsis, septic shock and bacteraemia. As assessed using ROC curves, CD64 was better than PCT for differentiating SIRS from severe sepsis and septic shock. CD64 and CD64/CD16 were associated with mortality.

CONCLUSIONS

CD64 and CD16 were differentially modulated by sepsis. CD64, CD64/CD16 and PCT may be biomarkers of sepsis. CD64 was better than PCT for identifying patients who required treatment with antibiotics.

Analysis of the temperature affects on leukocyte surface antigen expression

Flow cytometric analysis of leukocyte surface antigens has been used to characterize infectious and septic processes in patients. We wanted to investigate how the sampling and processing temperature, the anticoagulant used, and the storage of the sample influence leukocyte immunophenotyping. Four blood samples, two using acid citrate dextrose and two using heparin as an anticoagulant, were taken from five intensive-care unit patients with severe sepsis and five healthy volunteers. The samples were collected, stored, and processed either at +4°C or at room temperature (RT). The samples were processed for flow cytometric analysis within 1  hr of collection or after 6 or 24  hr storage. The surface antigens of interest were neutrophilic CD11b and CD64, monocytic CD11b, CD14, CD40, CD64, CD80 and HLA-DR, and lymphocytic CD69 (separately in CD4+ and CD8+ T cells, B cells, and natural killer cells). The fluorescence intensities were higher at RT than at +4°C. During storage the intensities increased at RT, but at +4°C there were only minor changes. The effects were similar with both anticoagulants studied. According to our results, flow cytometric analysis of leukocyte surface antigen expressions should be performed using +4°C temperature throughout the process and within 6  hr.

Increased CD64 expression on polymorphonuclear neutrophils indicates infectious complications following solid organ transplantation

The aim of this study was to evaluate the diagnostic value of monitoring CD64 antigen upregulation on polymorphonuclear neutrophils (PMN) for the identification of infectious complications in the postoperative course of solid organ transplanted patients. Twenty-five kidney, 13 liver, and four pancreas-kidney transplanted patients were included. Beginning with preoperative values up to postoperative values after 3 months for each patient, the PMN CD64 Index, HLA-DR on monocytes, NKp44+ NK and NK/T cells, CXCR3+ NK cells, CXCR3+ T helper cells, CXCR3+ NK/T cells, and CD4/CD8 ratio were measured by flow cytometry. Subsequently they were correlated with confirmed postoperative complications. Measuring the PMN CD64 Index reached a sensitivity of 89% and a specificity of 65% in the detection of infectious complications. Concerning this matter, it was a significantly better marker than all other included parameters except CXCR3+ NK/T cells. In contrast, according to our results the PMN CD64 Index has no diagnostic relevance in detection of rejections. The combination of included parameters showed no improved diagnostic value. Due to its high sensitivity and specificity for infectious complications CD64 on PMN could be proven a very good indicator in evaluating suspected infectious complications in the postoperative course of transplanted patients.

Neutrophil CD64: diagnostic accuracy and prognostic value in patients presenting to the emergency department

The purpose of this study was to evaluate the diagnostic accuracy and prognostic value of neutrophil CD64 expression for bacterial infection in febrile adult patients presenting to our hospital emergency department. We prospectively included 132 patients with fever ≥ 38ºC (≥ 100.4ºF) during the last 24 hours and we measured CD64 expression on neutrophils the day after admission at the emergency department. We followed the patients until full recovery or death. There were 115 (87%) patients with bacterial infection and 108 (94%) of them survived. There were 17 (13%) patients without bacterial infection and 12 (71%) of them survived. Patients with bacterial infection and patients who survived showed a CD64 index higher when compared with patients without bacterial infection and patients who died, respectively (3.7 ± 3.2 vs. 2.5 ± 2.3; p = 0.03; and 3.7 ± 3.1 vs. 1.7 ± 0.6; p = 0.002; Mann-Whitney U test). The receiver operating characteristic (ROC) curve analysis for detecting bacterial infection and predicting survival with the CD64 index showed an area under curve (AUC) of 0.66 (95% CI, 0.52-0.8; p = 0.03) and 0.71 (95% CI, 0.57-0.85; p = 0.01), respectively. Diagnostic accuracy and prognostic value of CD64 expression was good in adult patients with fever.

Flow cytometry developments and perspectives in clinical studies: examples in ICU patients

Septic syndromes represent a major, although largely under-recognized, healthcare problem worldwide accounting for thousands of deaths every year. Although flow cytometry (FCM) remains a relatively confidential diagnostic tool, it is useful at every step of intensive care unit (ICU) patients' management. This review will focus on biomarkers measurable by FCM on a routine standardized basis and usable for the diagnosis of sepsis and for prediction of adverse outcome, occurrence of secondary nosocomial infections or guidance of putative immunotherapy relative to innate and adaptive immune dysfunctions in ICU patients. Regarding early diagnosis of infection, neutrophil CD64 has been shown to be a highly sensitive and specific marker for systemic infection and sepsis in adults, neonates, and children. A diminished monocyte HLA-DR expression is a reliable marker for the development of monocyte anergy, secondary nosocomial infection, and death in critically ill patients. Finally, the measurement of an increased CD4(+)CD25(+)CD127(low) regulatory T cell percentage may represent a reliable marker for the diagnosis of lymphocyte dysfunctions in these patients. These stainings can be performed using lyse-no-wash methods and results are available within 1 h. Ideally, these biomarkers should be part of a panel helping to define ICU patients' immune status. In the specific clinical context of ICU patients' monitoring, the increasing potential of FCM is further illustrated by the use of the biomarkers listed above as stratification tools in preliminary clinical studies. The next critical step is to use these standardized FCM protocols in large multicentric clinical trials testing individualized immunotherapy. Importantly, many other markers of immune dysfunction are currently under development that could further enable the administration of targeted individualized therapy in ICU patients.