Neutrophils from term and preterm newborn infants express the high affinity Fcgamma-receptor I (CD64) during bacterial infections

Refining empiric subgroups of pediatric sepsis using machine-learning techniques on observational data

Sepsis contributes to 1 of every 5 deaths globally with 3 million per year occurring in children. To improve clinical outcomes in pediatric sepsis, it is critical to avoid "one-size-fits-all" approaches and to employ a precision medicine approach. To advance a precision medicine approach to pediatric sepsis treatments, this review provides a summary of two phenotyping strategies, empiric and machine-learning-based phenotyping based on multifaceted data underlying the complex pediatric sepsis pathobiology. Although empiric and machine-learning-based phenotypes help clinicians accelerate the diagnosis and treatments, neither empiric nor machine-learning-based phenotypes fully encapsulate all aspects of pediatric sepsis heterogeneity. To facilitate accurate delineations of pediatric sepsis phenotypes for precision medicine approach, methodological steps and challenges are further highlighted.

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.

Assessment of bacterial exposure on phagocytic capability and surface marker expression of sputum macrophages and neutrophils in COPD patients

Defective phagocytosis has been shown in chronic obstructive pulmonary disease (COPD) bronchoalveolar lavage and blood monocyte-derived macrophages. Phagocytic capabilities of sputum macrophages and neutrophils in COPD are unknown. We investigated phagocytosis in these cells from COPD patients and controls. Phagocytosis of Streptococcus pneumoniae or fluorescently labelled non-typeable Haemophilus influenzae (NTHi) by sputum macrophages and neutrophils was determined by gentamycin protection assay (COPD; n = 5) or flow cytometry in 14 COPD patients, 8 healthy smokers (HS) and 9 healthy never-smokers (HNS). Sputum macrophages and neutrophils were differentiated by adherence for the gentamycin protection assay or receptor expression (CD206 and CD66b, respectively), by flow cytometry. The effects of NTHi on macrophage expression of CD206 and CD14 and neutrophil expression of CD16 were determined by flow cytometry. There was greater uptake of S. pneumoniae [~10-fold more colony-forming units (CFU)/ml] by sputum neutrophils compared to macrophages in COPD patients. Flow cytometry showed greater NTHi uptake by neutrophils compared to macrophages in COPD (67 versus 38%, respectively) and HS (61 versus 31%, respectively). NTHi uptake by macrophages was lower in HS (31%, p = 0.019) and COPD patients (38%, p = 0.069) compared to HNS (57%). NTHi uptake by neutrophils was similar between groups. NTHi exposure reduced CD206 and CD14 expression on macrophages and CD16 expression on neutrophils. Sputum neutrophils showed more phagocytic activity than macrophages. There was some evidence that bacterial phagocytosis was impaired in HS sputum macrophages, but no impairment of neutrophils was observed in HS or COPD patients. These results highlight the relative contributions of neutrophils and macrophages to bacterial clearance in COPD.

Procalcitonin Clearance, CD64, and HLA-DR as Predictors of Outcome in Febrile Neutropenic Children With Lymphoreticular Malignancies

BACKGROUND

Febrile neutropenia (FN) is a dreaded complication of cancer chemotherapy. There has been a lot of improvement in supportive care in FN that has drastically reduced the infection-related mortality in these patients. The focus now is on reducing infection-related morbidity, healthcare costs and optimizing the quality of life of the child as well as their family during these episodes. In this study, biomarkers were studied as predictors of outcome so that outcome can be predicted earlier, and treatment modified accordingly.

OBJECTIVE

To measure procalcitonin levels (at baseline and day 3), procalcitonin clearance, neutrophil CD64 expression levels (at baseline) and monocyte HLA-DR expression levels (at baseline), and their correlation with outcome.

SETTING

Tertiary care hospital.

STUDY TYPE

Cross-sectional observational study.

POPULATION/PARTICIPANTS

Sixty-five episodes of FN in children below 12 years with lymphoreticular malignancies. Children receiving antibacterial and/or antifungal treatment within the last 7 days were excluded from the study.

METHODS

The subjects recruited into the study had undergone complete clinical and laboratory evaluation as per hospital protocol. Procalcitonin (day 0 and 3), neutrophil CD64 expression, and monocytic HLA-DR expression levels were measured in these patients.

RESULTS

Sixty-five episodes of FN were studied in children with lymphoreticular malignancy. It was found that procalcitonin and HLA-DR are very good markers of outcome, whereas CD64 although a good marker, was inferior to procalcitonin and HLA-DR in predicting outcome. Procalcitonin clearance was found to be superior to single value of procalcitonin. Furthermore, procalcitonin on day 3 was found to be a better predictor of outcome compared with its baseline value. Also, it was found that procalcitonin and HLA-DR had a significant correlation with baseline C-reactive protein levels.

CONCLUSIONS

On the basis of the findings of the study we suggest that serial monitoring of procalcitonin levels be used in febrile neutropenic children with cancer. Procalcitonin levels on day 3 alone can be offered in resource poor setting. The role of HLA-DR and CD64 also seems promising and needs to be further explored in larger multicentric studies.

Differential Accumulation and Activation of Monocyte and Dendritic Cell Subsets in Inflamed Synovial Fluid Discriminates Between Juvenile Idiopathic Arthritis and Septic Arthritis

Despite their distinct etiology, several lines of evidence suggest that innate immunity plays a pivotal role in both juvenile idiopathic arthritis (JIA) and septic arthritis (SA) pathophysiology. Indeed, monocytes and dendritic cells (DC) are involved in the first line of defense against pathogens and play a critical role in initiating and orchestrating the immune response. The aim of this study was to compare the number and phenotype of monocytes and DCs in peripheral blood (PB) and synovial fluid (SF) from patients with JIA and SA to identify specific cell subsets and activation markers associated with pathophysiological mechanisms and that could be used as biomarkers to discriminate both diseases. The proportion of intermediate and non-classical monocytes in the SF and PB, respectively, were significantly higher in JIA than in SA patients. In contrast the proportion of classical monocytes and their absolute numbers were higher in the SF from SA compared with JIA patients. Higher expression of CD64 on non-classical monocyte was observed in PB from SA compared with JIA patients. In SF, higher expression of CD64 on classical and intermediate monocyte as well as higher CD163 expression on intermediate monocytes was observed in SA compared with JIA patients. Moreover, whereas the number of conventional (cDC), plasmacytoid (pDC) and inflammatory (infDC) DCs was comparable between groups in PB, the number of CD141⁺ cDCs and CD123⁺ pDCs in the SF was significantly higher in JIA than in SA patients. CD14⁺ infDCs represented the major DC subset in the SF of both groups with potent activation assessed by high expression of HLA-DR and CD86 and significant up-regulation of HLA-DR expression in SA compared with JIA patients. Finally, higher activation of SF DC subsets was monitored in SA compared with JIA with significant up-regulation of CD86 and PDL2 expression on several DC subsets. Our results show the differential accumulation and activation of innate immune cells between septic and inflammatory arthritis. They strongly indicate that the relative high numbers of CD141⁺ cDC and CD123⁺ pDCs in SF are specific for JIA while the over-activation of DC and monocyte subsets is specific for SA.

The History of Biomarkers: How Far Have We Come?

Sepsis is one of the oldest and most elusive syndromes in medicine that is still incompletely understood. Biomarkers may help to transform sepsis from a physiologic syndrome to a group of distinct biochemical disorders. This will help to differentiate between systemic inflammation of infectious and noninfectious origin and aid therapeutic decision making, hence improve the prognosis for patients, guide antimicrobial therapy, and foster the development of novel adjunctive sepsis therapies. To reach this goal requires increased systematic investigation that includes twenty-first century scientific approaches and technologies and appropriate clinical evaluation.

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.

Examining the utility of the CD64 index compared with other conventional indices for early diagnosis of neonatal infection

As specific clinical manifestations and detection tools for early neonatal infections are lacking, early detection and treatment are ongoing challenges. The present study aimed to investigate the role and clinical significance of the CD64 index in comparison with conventional examination indices (WBC, PCT and CRP) for the early diagnosis of neonatal infection. Of 74 in-patient newborns, non-sepsis (non-specific infection but free of sepsis), sepsis and control [newborns with ABO hemolytic disease of the newborn (ABOHDN) but without infection] groups involved 32, 16 and 26 cases, respectively. Peripheral blood WBC, PCT, CRP and CD64 indices were acquired for all groups. The sepsis group showed significantly higher WBC, PCT and CRP levels than the control group. Compared with the non-sepsis group, the sepsis group demonstrated significant increases in PCT but not in WBC or CRP. Compared with the control group, the non-sepsis and sepsis groups had higher CD64 indices. Combined, compared with the WBC, PCT and CRP indices, the CD64 index is unique in its capacity to diagnose neonatal infections early. The CD64 index combined with other conventional indices may lay a basis for the future early diagnosis and effective treatment of neonatal infections.

Neutrophil CD64 combined with PCT, CRP and WBC improves the sensitivity for the early diagnosis of neonatal sepsis

BACKGROUND

The aim of this study was to determine whether neutrophil CD64 (nCD64) combined with procalcitonin (PCT), C-reactive protein (CRP) and white blood cell count (WBC) can increase the sensitivity and accuracy of neonatal sepsis diagnosis.

METHODS

The serum levels of nCD64, CRP, PCT and WBC were detected in 60 patients with neonatal sepsis and 60 patients with non-sepsis. Sensitivity, specificity, positive and negative predictive values, receiver operating characteristic (ROC) area under the curve (AUC), and logistic regression analysis were performed to evaluate the diagnostic value of these markers on neonatal sepsis.

RESULTS

Serum levels of nCD64, PCT, CRP and WBC were higher in the sepsis group than non-sepsis group (p<0.001). The sensitivities of nCD64, PCT, CRP and WBC at the recommended cut-off level for all infants were 79.5%, 68.2%, 38.6% and 52.3%, respectively. The best combination was nCD64 and PCT, which obtained sensitivity of 90.9%, largest AUC of 0.922, and a negative predictive value of 89.2%. However by using an optimal cut-off value, the sensitivities of all four biomarkers for the diagnosis of neonatal sepsis were increased to 95.5%. Except for WBC, the birth weight and gestational age had no effects on the diagnostic value of these serum biomarkers.

CONCLUSIONS

nCD64 and PCT are better diagnostic biomarkers for early diagnosis of neonatal sepsis as compared to CRP. With the help of optimal cut-off value based on ROC curve and logistic regression analysis, the combination of these biomarkers could improve the sensitivity for the diagnosis of suspected late-onset neonatal sepsis based on common serum biomarkers.

Early and Late Infections in Newborns: Where Do We Stand? A Review

Neonatal sepsis still represents an important cause of mortality and morbidity among infants. According to the onset, we can distinguish "early onset sepsis" when microbiological cultures positive for external pathogens come from newborns during the first 7 days of life (maternal intrapartum transmission); "late onset sepsis" when microbiological cultures positive for external pathogens come from newborns after the first 7 days from delivery (postnatal acquisition). In this review we synthesize the incidence, risk factors, clinical manifestations, and methods of diagnosis and treatment of each type of neonatal infection, in order to better define such a pathological condition which is of great importance in common clinical practice.

Early detection of neonatal group B streptococcus sepsis and the possible diagnostic utility of IL-6, IL-8, and CD11b in a human umbilical cord blood in vitro model

Background

Group B streptococcus (GBS) infection remains a major cause of neonatal morbidity and mortality, and GBS III is the predominant strain in early-onset GBS neonatal sepsis. To avoid both over- and undertreatment of infants with nonspecific signs of infection, early diagnostic tools are warranted. The aim of this study was to identify biomarkers with high sensitivity and specificity in an early stage of GBS infection. A secondary aim was to assess the utility of a human umbilical cord blood (HUCB) model system of early-onset neonatal sepsis.

Methods

Umbilical cord blood samples from 20 healthy term pregnancies were stimulated for 2 hours with a GBS III isolate from a patient and a commercially available GBS Ia strain. Nonstimulated samples served as controls. Leukocyte surface markers (CD11b, CD64, toll-like receptor [TLR] 2, TLR4, and TLR6) were analyzed by flow cytometry and soluble biomarkers by enzyme-linked immunosorbent assay (interleukin [IL]-6 and -8; interferon-γ-inducing protein [IP]-10; and S100b). The area under the receiver operating characteristic curve (AUC) was calculated for the markers.

Results

GBS III gave the highest responses and AUC values for all biomarkers. Only IL-6 and IL-8 displayed an AUC approaching 0.8 for both GBS serotypes (P<0.001). IL-8 >5,292 pg/mL had both a sensitivity and a specificity of 1.00. IL-6 >197 pg/mL had both a sensitivity and a specificity of 0.95 for GBS III stimulation. CD11b on granulocytes and monocytes was the leukocyte surface marker with the highest AUC values for both GBS serotypes.

Conclusion

In agreement with previous studies, IL-6, IL-8, and potentially CD11b could be useful in diagnosing neonatal GBS infection in an early stage. Our HUCB early-onset neonatal sepsis model may be useful for evaluating biomarkers of neonatal sepsis. The HUCB of neonates with risk factors for sepsis might even be used for diagnostic purposes, but requires further study.

The usefulness of neutrophil CD64 expression for diagnosing infection after orthopaedic surgery in dialysis patients

BACKGROUND

Dialysis patients undergoing orthopaedic surgery are at high risk for postoperative infection. Diagnosis of postoperative infection is difficult in dialysis patients due to presentation of signs and symptoms similar to infection, such as fever and elevated inflammatory marker levels. Neutrophil CD64 expression (CD64), a marker of infection, is upregulated by microbial wall components and several cytokines (interferon-γ and tumor necrosis factor-α). The purpose of this study is to evaluate the usefulness of CD64 for diagnosing postoperative infection in dialysis patients post orthopaedic surgery.

PATIENTS AND METHODS

Between 2013 and 2014, we prospectively studied 36 dialysis patients (18 men, 18 women; mean age 65.9 years; 49 to 83) who underwent orthopaedic surgery. Dialysis patients were classified into three groups according to their postoperative course as follows; non-infected patients, infection suspected patients, and infected patients. Inflammatory markers such as white blood cell count (WBC), C-reactive protein (CRP) and CD64 were measured before operation and one week after surgery. Using the receiver-operating characteristic (ROC) curve and Akaike's Information Criterion (AIC), the cutoff value of CD64 and CRP was calculated leading to a determination of which inflammatory marker is best accurate for detecting postoperative infection.

RESULTS

We found that postoperative CD64 and CRP levels presented a statistically significant difference between infected patients and non-infected patients (p < 0.05). Furthermore, comparison of the ROC curve and AIC value between postoperative CD64 and CRP levels exhibited that CD64 was more accurate infectious marker than CRP.

CONCLUSION

CD64 is a useful marker for detecting postoperative infection after orthopaedic surgery in dialysis patients.

Clinical application of neutrophil CD64 quantification for differential diagnosis of acute scrotum

The management of acute scrotum can be challenging, especially in infants or patients with a neurological or neurodevelopmental disorder in whom presentation, diagnosis and definitive management tends to be delayed. This leads to poor outcomes, such as loss of the affected testis. Here we present two cases of testicular torsion in patients with neurodevelopmental disorders, and a further two cases of epidydimo-orchitis in whom measurement of CD64 expression on neutrophils was helpful for differential diagnosis. These data suggest that the levels of expression of CD64 by neutrophils, known as a marker of infection, could also be useful for differentiating between testicular torsion and infection in acute scrotum.

Neutrophil CD64 is upregulated in RA patients with lymphoma but not in other solid cancers

OBJECTIVE

To evaluate the utility of quantifying CD64 expression on neutrophils in rheumatoid arthritis patients with malignancy, especially its diagnostic role in lymphoma.

METHODS

We used flow cytometry to quantify CD64 expression on neutrophils from patients diagnosed with malignancy during the follow-up period prior to initiating treatment.

RESULTS

Neutrophils from 18 patients with lymphoma expressed significantly higher levels of CD64 (9635.6 ± 2123.7 molecules/cell) than those from 32 patients with other solid cancers (carcinoma) (1250.5 ± 91.1 molecules/cell) (p < 0.001). When the cutoff value was set at 2060 molecules/cell, the sensitivity and specificity of CD64 for diagnosing lymphoma was 88.9% and 94.4%, respectively.

CONCLUSIONS

The quantitative measurement of neutrophil CD64 by flow cytometry may be useful as a subsidiary diagnostic marker in patients with suspected lymphoma. Although neutrophil CD64 is currently a well-known marker of infection, it is necessary to bear in mind that lymphoma is also a candidate in differential diagnosis when CD64 expression on neutrophils is upregulated.

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.

Role of Neutrophil CD64 Index as a Screening Marker for Late-Onset Sepsis in Very Low Birth Weight Infants

Introduction

The role of CD64 in late onset sepsis (LOS) in preterm infants has been described in several studies. Aim of this study was to investigate whether CD64 expression is increased in the days before clinical manifestation of LOS.

Methods

Patients with birth weight below 1,500g were eligible for study participation. During routine blood sampling CD64 index was determined between day of life 4 and 28. Patients were allocated to one of four groups: (1) blood-culture positive sepsis, (2) clinical sepsis, (3) symptoms of infection without biochemical evidence of infection, or (4) patients without suspected infection. Kinetics of CD64 expression were compared during a period before and after the day of infection in the respective groups.

Results

50 infants were prospectively enrolled and allocated to each group as follows: group (1) n = 7; group (2) n = 10; group (3) n = 8; and group (4) n = 25. CD64 index was elevated in 57% of patients in group (1) at least two days before infection. In contrast only 20% in the clinical sepsis group and 0% in group (3) had an elevated CD64 index in the days before infection. 10 of the 25 patients in the control group (4) presented increased CD64 index values during the study period.

Conclusions

The CD64 index might be a promising marker to detect LOS before infants demonstrate signs or symptoms of infection. However, larger prospective studies are needed to define optimal cut-off values and to investigate the role of non-infectious inflammation in this patient group.

Diagnostic value of blood gene expression signatures in active tuberculosis in Thais: a pilot study

Tuberculosis (TB) is a major global health problem. Routine laboratory tests or newly developed molecular detection are limited to the quality of sputum sample. Here we selected genes specific to TB by a minimum redundancy-maximum relevancy package using publicly available microarray data and determine level of selected genes in blood collected from a Thai TB cohort of 40 active TB patients, 38 healthy controls and 18 previous TB patients using quantitative real-time PCR. FCGR1A, FCGR1B variant 1, FCGR1B variant 2, APOL1, GBP5, PSTPIP2, STAT1, KCNJ15, MAFB and KAZN had significantly higher expression level in active TB individuals as compared with healthy controls and previous TB cases (P<0.01). A mathematical method was applied to calculate TB predictive score, which contains the level of expression of seven genes and this score can identify active TB cases with 82.5% sensitivity and 100% specificity as compared with conventional culture confirmation. In addition, TB predictive scores in active TB patients were reduced to normal after completion of standard short-course therapy, which was mostly in concordant with the disease outcome. These finding suggested that blood gene expression measurement and TB Sick Score could have potential value in terms of diagnosis of TB and anti-TB treatment monitoring.

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.

Phagocytosis of neonatal pathogens by peripheral blood neutrophils and monocytes from newborn preterm and term infants

BACKGROUND

Deficiencies in phagocytosis may contribute to the increased susceptibility of infants to early life infections. Data on phagocytosis of the major neonatal pathogens Staphylococcus epidermidis (SE), Staphylococcus aureus (SA), and Escherichia coli (EC) by preterm infant leukocytes are inconsistent.

METHODS

Cord and <24-h peripheral blood were collected from very preterm (<30.1 wks gestational age (GA)) and term (37-42 wks GA) infants. Monocyte and neutrophil phagocytosis of pHrodo-labeled SE, SA, and EC were analyzed using a small-volume flow cytometry assay, with simultaneous characterization of surface activation marker expression.

RESULTS

Preterm infants had lower proportions of monocytes and neutrophils capable of phagocytosis than term infants, but preterm infant phagocytes had higher phagocytic capacity. Phagocytosis was strongly correlated between cord and <24-h peripheral blood. Supplementation with exogenous complement significantly increased phagocytosis of EC but not of SE or SA. Monocyte human leukocyte antigen (HLA)-DR expression was lower in preterm infants but did not correlate with phagocytosis.

CONCLUSION

There is no defect in phagocytosis by monocytes and neutrophils from preterm compared with term infants, although preterm infants possess fewer phagocytes, possibly contributing to susceptibility to bacterial infection. Further investigation into the development of postnatal phagocytic competence is warranted.

Neonatal sepsis: an old problem with new insights

Neonatal sepsis continues to be a common and significant health care burden, especially in very-low-birth-weight infants (VLBW <1500 g). Though intrapartum antibiotic prophylaxis has decreased the incidence of early-onset group B streptococcal infection dramatically, it still remains a major cause of neonatal sepsis. Moreover, some studies among VLBW preterm infants have shown an increase in early-onset sepsis caused by Escherichia coli. As the signs and symptoms of neonatal sepsis are nonspecific, early diagnosis and prompt treatment remains a challenge. There have been a myriad of studies on various diagnostic markers like hematological indices, acute phase reactants, C-reactive protein, procalcitonin, cytokines, and cell surface markers among others. Nonetheless, further research is needed to identify a biomarker with high diagnostic accuracy and validity. Some of the newer markers like inter α inhibitor proteins have shown promising results thereby potentially aiding in early detection of neonates with sepsis. In order to decrease the widespread, prolonged use of unnecessary antibiotics and improve the outcome of the infants with sepsis, reliable identification of sepsis at an earlier stage is paramount.

CD15s is a potential biomarker of serious bacterial infection in infants admitted to hospital

Early recognition of serious bacterial infection (SBI) in children is essential for better treatment outcome. Flow cytometry analysis of neutrophil surface molecules has been more frequently utilized as a tool for diagnosis of infection. The infants (n = 105) under 6 months of age presenting to the pediatric emergency department with fever without apparent source who were hospitalized with suspicion of having SBI were enrolled in this prospective study. Sixty-nine infants were included into the training pool and were classified into bacterial or viral infection group. Validation pool consisted of 36 infants. The values of white blood cells counts, absolute neutrophil count (ANC), C-reactive protein (CRP), procalcitonin (PCT), neutrophil CD11b, CD15s and CD64 expression, and the percentage (%CD15s+) and absolute count (AC-CD15s+) of CD15s+ neutrophils were determined. In infants with SBI, %CD15s+ was 10.5 times more likely to be higher than the cut-off value. ANC, CRP, PCT, CD64, and AC-CD15s+ were also found as useful biomarkers for differentiation between bacterial and viral infection. The best fit multivariate logistic regression model included CRP, PCT, and %CD15s+ as strong predictors of SBI. The model's sensitivity (87 %) and specificity (83 %) indicated high model's accuracy. After validation on independent dataset, model's accuracy maintained high: 86 % sensitivity and 93 % specificity, confirming its reliability and supporting CRP, PCT, and %CD15s+ as real predictors. The findings of this study support assumption made in the literature on significance of CD15s in inflammation processes. Also, this study demonstrated for the first time that CD15s is potentially valuable biomarker of SBI in infants.

Normal sequential changes in neutrophil CD64 expression after total joint arthroplasty

BACKGROUND

Neutrophil CD64 has been reported to be a sensitive and specific infection marker. Its measurement is thus considered to be useful in early diagnosis of post-operative periprosthetic infection. However, even its normal sequential changes after non-infectious total joint arthroplasty have remained ambiguous. Accordingly, we analyzed 2-week sequential neutrophil CD64 expression changes after total joint arthroplasty in order to clarify its normal postoperative kinetics.

PATIENTS AND METHOD

From 41 patients who underwent primary total joint arthroplasties, peripheral blood samples were obtained at 1 day before (baseline) and 1, 3, 5, 7, and 14 days after surgery, and CD64 expression per cell was quantitatively measured. C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR) and white blood cell count (WBC) were simultaneously measured.

RESULTS

No cases of postoperative local infection were observed. Levels of CD64 significantly elevated from day 1, peaked at day 3, and decreased significantly following day 5. Statistical analysis confirmed that significant differences existed between the baseline level and the levels at days 1 and 3, while no significant differences existed between the baseline level and those at days 5, 7 or 14. In 17 patients, CD64 peaked at over 2,000 molecules/cell, the level reported to be a cutoff value for distinguishing infection. Multiple regression analysis showed that the sole parameter of baseline CD64 level significantly explained the peak CD64 level. Postoperative CD64 peaks ranged from 1.6 to 2.7 times (median 1.9) the baseline levels. CRP, ESR and WBC also showed rapid elevations and all but WBC remained significantly higher than baseline at day 14.

CONCLUSION

CD64 levels rise significantly, peaking within about 3 days following normal total joint arthroplasty, but decrease rapidly to near baseline within about 5 days. The data obtained can be expected to form a possible basis for early diagnosis of postoperative periprosthetic infection.

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.

Comparison of the accuracy of neutrophil CD64 and C-reactive protein as a single test for the early detection of neonatal sepsis

Purpose

Early identification of neonatal sepsis is a global issue because of limitations in diagnostic procedures. The objective of this study was to compare the diagnostic accuracy of neutrophil CD64 and C-reactive protein (CRP) as a single test for the early detection of neonatal sepsis.

Methods

A prospective study enrolled newborns with documented sepsis (n=11), clinical sepsis (n=12) and control newborns (n=14). CRP, neutrophil CD64, complete blood counts and blood culture were taken at the time of the suspected sepsis for the documented or clinical group and at the time of venipuncture for laboratory tests in control newborns. Neutrophil CD64 was analyzed by flow cytometry.

Results

CD64 was significantly elevated in the groups with documented or clinical sepsis, whereas CRP was not significantly increased compared with controls. For documented sepsis, CD64 and CRP had a sensitivity of 91% and 9%, a specificity of 83% and 83%, a positive predictive value of 83% and 33% and a negative predictive value of 91% and 50%, respectively, with a cutoff value of 3.0 mg/dL for CD64 and 1.0 mg/dL for CRP. The area under the receiver-operating characteristic curves for CD64 index and CRP were 0.955 and 0.527 (P<0.01), respectively.

Conclusion

These preliminary data show that diagnostic accuracy of CD64 is superior to CRP when measured at the time of suspected sepsis, which implies that CD64 is a more reliable marker for the early identification of neonatal sepsis as a single determination compared with CRP.

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.

Neutrophil CD64 expression in inflammatory autoimmune diseases: its value in distinguishing infection from disease flare

The purpose of this research was to clarify the significance of neutrophil CD64 expression in discrimination between infection and disease flare in patients with inflammatory autoimmune diseases. The study included 63 subjects, 20 healthy controls and 43 patients with inflammatory autoimmune diseases (24 with rheumatoid arthritis & 19 with systemic lupus erythematosus). The FC gamma receptor I (CD64 expression) on neutrophils was measured using flow cytometry. The intensity of CD64 expression on neutrophils was significantly elevated in patients with infections; 49.0 (13-205), and active autoimmune disease; 36.15 (12-133) compared to healthy controls; 5.35 (2.6-14) or patients with inactive disease; 7.5 (3.3-18). In the infectious disease group, expression of CD64 was significantly higher than in the active inflammatory disease group, while there was no significant difference between the group of patients with inactive inflammatory disease and healthy controls (P > 0.05). The sensitivity of CD64 bearing neutrophil intensity for detection of infection (using a cut off value of ≥43.5) was 94.4% and specificity was 88.9%. Neutrophil CD64 expression has a good sensitivity and specificity in differentiating infection from disease flare in patients with inflammatory autoimmune diseases. This assay could facilitate early and accurate diagnosis and greatly aid timely institution of appropriate treatment.

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.

Predictive values of neutrophil CD64 expression compared with interleukin-6 and C-reactive protein in early diagnosis of neonatal sepsis

BACKGROUND

Despite major advances in the management of newborn infants, neonatal sepsis (NS) remain important causes of neonatal morbidity and mortality in the newborn, mainly among preterm and low birth weight infants.

OBJECTIVE

The aim of this study was to investigate the usefulness of neutrophil CD64 expression alone and together with other infection markers in NS.

METHODS

Peripheral blood samples were taken from 109 neonates, who were categorized into three groups: proven or clinical sepsis (n=35); disease without infection (n=42); and healthy controls (n=32). Complete blood count with differential, interleukin-6 (IL-6), C-reactive protein (CRP), and cell surface expression of CD64 on neutrophils have been evaluated in a prospective manner as a diagnostic aid for NS.

RESULTS

Expression of CD64 was significantly enhanced in neonates with sepsis compared with newborns with disease without infection and healthy controls (P=0.001 and P=0.001, respectively). Cutoff values of IL-6, CRP, CD64(MFI), and CD64(i) were 24.9  pg/ml, 4.05  mg/l, 87.7, and 4.39, respectively. Sensitivity-negative predictive values of IL-6, CRP, and CD64(MFI)/CD64(i) were 80.0-90.6%, 80.0-88.8%, and 88.6-94.0%, respectively. Combining all three tests increased the sensitivity to 100%; however, specificity and positive predictive value decreased to 62.1 and 55.5%, respectively.

CONCLUSIONS

CD64 might be used either alone or combined with IL-6 and CRP for early diagnosis of NS. The advantages of CD64 when compared with IL-6 and CRP are rapid quantitation, very small blood volume required, and easy handling.

The usefulness of neutrophil CD64 expression in the diagnosis of local infection in patients with rheumatoid arthritis in daily practice

BACKGROUND

The diagnosis of local infection in patients with rheumatoid arthritis (RA) is frequently difficult because clinical signs and symptoms and laboratory test results of local infection are also observed in arthritis of active RA. The need for a specific marker of infection is high in RA patients. The usefulness of neutrophil CD64 expression (CD64) to diagnose local musculoskeletal infection (local infection) and discriminate local infection from RA-related inflammation in RA patients was examined.

METHODS

CD64 was measured by a quantitative method using flow cytometry in 61 RA patients in whom local infection was suspected, and the usefulness of CD64 was examined by comparing the findings with clinical results.

RESULTS

There were 25 patients with local infection and 36 patients without infection. The median CD64 value the patients with local infection was 3148 molecules/cell (interquartile range [IQR], 2140-6231) and that of the patients without infection was 1106 molecules/cell (IQR, 804-1464) with a statistically significant difference (P < 0.0001). In contrast, no significant difference between the groups was observed in C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell (WBC) count. The area under the curve of CD64 calculated by receiver operating characteristic curve analysis was larger than that of CRP, ESR, or WBC count, suggesting that CD64 has superior ability to discriminate of infection compared to these other markers. When the cutoff value of CD64 was set at 2000 molecules/cell, the sensitivity and specificity of CD64 for the detection of local infection in RA patients were 76.0% and 94.4%, respectively.

CONCLUSIONS

CD64 is a useful marker in RA patients to discriminate local infection from RA-related inflammation.

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

The usefulness of neutrophil CD64 expression was examined in diagnosing local infection, including soft tissue, bone, and joint infections. Among 99 patients suspected of local infection, 31 were confirmed and 68 patients were not. The CD64 level of patients with local infection was significantly higher than in those without infection [4,193 ± 1,132 vs. 1,017 ± 59 molecules/cell (mean ± standard deviation); p < 0.001]. The area under the curve of CD64 calculated by receiver operating characteristic curve analysis was larger than that of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), or white blood cell (WBC) count. In addition, CD64 levels of patients with crystal-induced arthritis remained within cutoff value (2,000 molecules/cell). These data suggest that measuring CD64 expression can be a useful diagnostic marker for local musculoskeletal infection and crystal-induced arthritis.

Neutrophil CD64 expression as marker of bacterial infection: a systematic review and meta-analysis

OBJECTIVE

We performed a systematic review and meta-analysis of studies to evaluate the diagnostic accuracy of expression of CD64 on polymorphonuclear neutrophils (PMN) as a marker for bacterial infection.

METHODS

The analysis included studies of patients from all age groups that prospectively evaluated CD64 expression on PMNs for the diagnosis of bacterial infection. We evaluated the methodological quality of the studies according to the 25-item criteria developed by the Standards for Reporting of Diagnostic Accuracy (STARD) committee. We calculated a summary receiver operating characteristic (SROC) curve across studies included in the meta-analysis.

RESULTS

The methodological quality score of the 13 included studies ranged from 9 to 16 points (maximum score was 25 points). The pooled sensitivity and specificity for CD64 expression on PMNs were 79% (95% CI: 70-86%) and 91% (95% CI: 85-95%), respectively. The area under curve (AUC) was 0.94.

CONCLUSIONS

On the basis of this meta-analysis, CD64 expression on PMNs could be a useful diagnostic cell-based parameter of bacterial infections. However, published studies about this topic showed a low methodological quality.

Neutrophil and monocyte CD64 indexes, lipopolysaccharide-binding protein, procalcitonin and C-reactive protein in sepsis of critically ill neonates and children

OBJECTIVE

To compare the diagnostic accuracy of neutrophil and monocyte CD64 indexes (CD64in and CD64im) for sepsis in critically ill neonates and children with that of lipopolysaccharide-binding protein (LBP), procalcitonin (PCT) and C-reactive protein (CRP).

DESIGN AND SETTING

Prospective, observational study in a level III multidisciplinary neonatal and pediatric intensive care unit (ICU).

PATIENTS

Forty-six neonates and 36 children with systemic inflammatory response syndrome (SIRS) and suspected infection, classified into two groups: those with bacterial sepsis (microbiologically proven or clinical sepsis) and those without bacterial sepsis (infection not supported by subsequent clinical course, laboratory data and microbiological tests).

INTERVENTIONS AND MEASUREMENTS

Flow cytometric CD64in and CD64im, serum LBP, PCT and CRP measurement on 2 consecutive days from admission to the ICU.

RESULTS

There were 17 cases of bacterial sepsis in neonates and 24 cases of bacterial sepsis in children. All neonates and the majority of children were mechanically ventilated, and more than two-thirds of neonates with sepsis and one-third of children with sepsis needed inotropic/vasopressor drugs. The highest diagnostic accuracy for sepsis on the 1st day of suspected sepsis was achieved by LBP in neonates (0.86) and by CD64in in children (0.88) and 24 h later by CD64in in neonates (0.96) and children (0.98).

CONCLUSIONS

Neutrophil CD64 index (CD64in) is the best individual marker for bacterial sepsis in children, while in neonates the highest diagnostic accuracy at the time of suspected sepsis was achieved by LBP and 24 h later by CD64in.

CD64 index provides simple and predictive testing for detection and monitoring of sepsis and bacterial infection in hospital patients

The rapid diagnosis and management of bacterial infection are heavily dependent upon clinical assessment. Blood culture may take up to 2 days for results and may be suspect. Surface neutrophil CD64 expression has been shown to be upregulated in cases of bacterial infection. Recently, a standardized kit for the CD64 index was used in neonatal intensive care units, showing high sensitivity and specificity for bacterial infections. Our study was designed to confirm and extend these results to adult hospital patients and to determine the impact of this testing on a clinical laboratory's finances and staffing. CD64 indices were performed with peripheral blood drawn in tandem with blood cultures from 109 patients over a 2-month period. We found that a CD64 index of <or=1.19 was predictive of "no growth" blood culture results. An index of >1.19 was predictive of an ultimate clinical and/or culture diagnosis of infection with a sensitivity and specificity of 94.6% and 88.7%, respectively. Positive and negative predictive values were 89.8% and 94%, respectively. The CD64 index was easily performed using our flow cytometer and staff, producing minimal alteration in clinical workflow. A 7-day-a-week testing schedule will result in some additional expense but will be more than offset by the expected cost savings. The CD64 index is a useful and inexpensive test for improving the diagnosis and management of hospital patients with bacterial infection. It can be readily performed by clinical laboratories and could result in considerable savings for the institution.

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

The expression of the Fcgamma-receptor I (FcgammaRI), CD64 on normal neutrophils is up-regulated during bacterial infections. CD64 is a promising diagnostic tool in the diagnosis of acute infections. The aim was to study surface expressions of CD64 on neutrophils and monocytes in patients with influenza A with and without complications and evaluate these as diagnostic tools in comparison with serum levels of HNL (human neutrophil lipocalin). CD64 expression on neutrophils and monocytes was evaluated by flow cytometry. HNL was assayed by a specific radioimmunoassay. 22 patients with influenza A with or without complications were included and the results compared with those of 29 patients with acute bacterial infections and 29 healthy subjects. Neutrophil expression of CD64 was increased in influenza A with raised proportion expressing CD64 in complicated compared to uncomplicated influenza. The expression was significantly higher in bacterial infections compared to both influenza groups. Serum levels of HNL were raised in all infection groups, but significantly more so in the group with bacterial infection. ROC-curve analysis showed that neutrophil expression of CD64 and the serum levels of HNL had similar diagnostic power in the discrimination between acute bacterial infections and influenza A. Monocyte expression of CD64 was raised in all infections with no differences between subgroups. We conclude that neutrophil expression of CD64 and serum levels of HNL are both promising assays in the distinction between infections caused by bacteria or influenza A, whereas CD64 could identify patients with complications of their influenza A infection.

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 CD64 expression as a diagnostic marker of bacterial infection in febrile children presenting to a hospital emergency department

BACKGROUND

The expression of CD64 (Fcgamma receptor) is increased in neutrophils from an almost negligible value to a marked level in patients with bacterial infections. CD64 expression on neutrophils might therefore be useful to differentiate between bacterial and viral infections in young children. We evaluated the usefulness of CD64 as a marker for the diagnosis of bacterial infections in children up to the age of 3 years and its ability to differentiate between bacterial and viral infections.

METHODS

Blood samples were drawn from 70 children aged 3 years or younger who presented to the pediatric emergency department with fever as their main complaint. Thirty-eight children were diagnosed as having bacterial infection and 32 as having viral infection. The control group included 39 healthy children. CD64, C-reactive protein (CRP), and procalcitonin levels were determined for each child. The sensitivity and specificity of these parameters were calculated.

RESULTS

Neutrophil expression of CD64 was significantly higher in the bacterial infection group compared with the viral infection and the control groups (P < 0.0001). Raising the cutoff for diagnosis of bacterial disease lowered the sensitivity but improved the specificity. CD64 was found to have a very high sensitivity (94.7%), but its specificity was poor (46.5%). No significant differences were found between the diagnostic performance of CD64 and that of CRP: both have high sensitivity and low specificity (94.7% and 47.9%, respectively, for CRP). In contrast, procalcitonin had a betterspecificity (91%), but its sensitivity reached only 71.9%. CD64 expression was increased in patients with respiratory syncytial virus-related infections compared with that in patients with other viral infections and was similar to that found during bacterial illness.

CONCLUSIONS

Neutrophil CD64 expression is a sensitive marker for diagnosing bacterial infection in young children, but as it is also raised in viral infection, it lacks specificity.

Neutrophil and monocyte CD64 and CD163 expression in critically ill neonates and children with sepsis: comparison of fluorescence intensities and calculated indexes

Objective. To evaluate the expression of CD64 and CD163 on neutrophils and monocytes in SIRS with/without sepsis and to compare the diagnostic accuracy of CD64 and CD163 molecules expression determined as (1) mean fluorescence intensities (MFI) of CD64 and CD163; and (2) the ratio (index) of linearized MFI to the fluorescence signal of standardized beads. Patients and methods. Fifty-six critically ill neonates and children with systemic inflammatory response syndrome (SIRS) and suspected sepsis, classified into two groups: SIRS with sepsis (n = 29) and SIRS without sepsis (n = 27). Results. CD64 and CD163 MFI measured on neutrophils and monocytes were elevated in patients with SIRS with sepsis. Diagnostic accuracy of indexes was equal to diagnostic accuracy of MFI for CD64 on neutrophils (0.833 versus 0.854 for day 0 and 0.975 versus 0.983 for day 1) and monocytes (0.811 versus 0.865 for day 0 and 0.825 versus 0.858 for day 1), and CD163 on neutrophils (0.595 versus 0.655 for day 0 and 0.677 versus 0.750 for day 1), but not for CD163 on monocytes. Conclusion. CD64 MFI, CD163 MFI, CD64 indexes for neutrophils and monocytes, and CD163 index for neutrophils can all be used for discrimination of SIRS and sepsis in critically ill neonates and children. CD64 index for neutrophils, however, is superior to all other markers.

Evaluation of neutrophil CD64 expression and procalcitonin as useful markers in early diagnosis of sepsis

Quantitation of neutrophil CD64 expression and procalcitonin (PCT) levels in blood samples have been recently proposed as useful tools for early detection of sepsis. To determine the usefulness of these tests, we analyzed blood samples of 112 patients, admitted to an intensive care unit (ICU), presenting clinical symptoms of sepsis, as well as of 50 healthy controls. At the end of the study, a retrospective analysis showed that only 52 of the 112 ICU-patients presented a real sepsis (positive blood culture). The results obtained indicated that of the 52 patients with sepsis, 50 and 49 presented levels of neutrophil CD64 expression >or= 2398 molecules per cell (cut-off determined by receiver operator characteristic analysis) and PCT levels >0.5 ng/ml (cut-off suggested by the manufacturer), respectively. However, the neutrophil CD64 test showed higher specificity in detecting sepsis since 5 out of the 60 ICU-patients without sepsis (negative blood culture), presented CD64 expression levels >or= 2398 molecules per cell, PCT levels >or= 0.5 ng/ml were shown in 27 patients. Moreover, while none of the 50 healthy controls presented a neutrophil CD64 level higher than the cut-off value, 5 patients presented PCT levels >or= 0.5 ng/ml. In conclusion, our data seem to indicate that the quantitation of CD64 expression could be taken into consideration as a sensitive and specific test for early diagnosis of sepsis.

Hematologic profile of sepsis in neonates: neutrophil CD64 as a diagnostic marker

OBJECTIVE

The goal was to determine the utility of neutrophil CD64 as a diagnostic marker for sepsis in neonates.

METHODS

A prospective study that enrolled consecutive infants with suspected sepsis was performed. Complete blood count with differential, blood culture, and CD64 index measurement were performed, and neutrophil CD64 indices were correlated with the diagnoses of confirmed and suspected sepsis.

RESULTS

There were 293 episodes of sepsis evaluations for 163 infants. Infants with sepsis episodes (confirmed or suspected; n = 40) were of greater gestational age (34.7 +/- 0.9 weeks), compared with those (n = 123) with no sepsis (32.6 +/- 0.5 weeks), but had similar birth weights (2325 +/- 200 vs 1969 +/- 94 g) and Apgar scores at 1 and 5 minutes. There was no difference in the duration of hospitalization for the 2 groups. As expected, the hematologic profiles of sepsis episodes (n = 128) were characterized by higher white blood cell counts, absolute neutrophil counts, absolute band counts, and immature/total neutrophil ratios but lower platelet counts. Sepsis episodes had higher neutrophil CD64 indices (5.61 +/- 0.85 vs 2.63 +/- 0.20). For all sepsis episodes, the CD64 index had an area under the curve, in receiver operating characteristic analysis, of 0.74; with a cutoff value of 2.30, the CD64 index in combination with the absolute neutrophil count had the highest negative predictive value (93%) for ruling out sepsis and 95% sensitivity for diagnosing sepsis. For culture-positive sepsis episodes, the CD64 index had the highest area under the curve (0.852) of all hematologic variables, with a sensitivity of 80% and a specificity of 79%, with a cutoff value of 4.02.

CONCLUSIONS

Neutrophil CD64 is a highly sensitive marker for neonatal sepsis. Prospective studies incorporating CD64 into a sepsis scoring system are warranted.

Hematological indices, inflammatory markers and neutrophil CD64 expression: comparative trends during experimental human endotoxemia

CD64 is a high-affinity Fc(gamma)RI receptor expressed by activated neutrophils that has been recently evaluated as a potential sepsis parameter. In the present study, the kinetics of neutrophil membrane CD64 expression were examined during a standardized inflammatory response, using a human endotoxemia model, and compared with hematological indices, CRP, cytokines and interleukins. Ten healthy subjects received 2 ng/kg intravenous Escherichia coli lipopolysaccharide (LPS). After administration of LPS, neutrophil CD64 showed a biphasic response, characterized by a first increase from 108.5 +/- 7.5 to 133 +/- 6 AFU after 1 h (P = 0.047) and a second increase that started at 6 h and reached its maximum of 167 +/- 13 AFU at 22 h (P < 0.0001). CRP concentrations increased to 40 +/- 5 mg/dl 22 h after the administration of LPS. The cytokines and interleukins reached their maximum response within 1-2 h. The maximum values of pro-inflammatory cytokines (TNF-alpha, IFN-gamma and IL-6) correlated with the CD64 expression at 22 h after LPS administration (r(2) = 0.76, r(2) = 0.78, r(2) = 0.81, respectively, all P < 0.05), whereas this correlation was not found for the anti-inflammatory IL-10 (r(2) = 0.058, P = 0.54), suggesting that neutrophil CD64 expression might be a quantitative marker for innate immunity that could easily be used in the clinical setting.

Newer approaches to the diagnosis of early onset neonatal sepsis

Accurate and timely diagnosis of early onset neonatal sepsis remains challenging to the clinician and the laboratory. A test with a rapid turnaround time with 100% sensitivity, rather than high specificity, which allows accurate diagnosis and appropriate antimicrobial treatment or which allows antibiotics to be safely withheld in non-infected infants, is desirable. Many potential markers (acute phase reactants, cell surface markers, cytokines) are not routinely available to the laboratory, and most likely combinations of markers will ensure greater diagnostic accuracy. In the future, molecular biology techniques offer the prospect of rapid identification of both pathogens and antimicrobial resistance markers.

Simultaneous determination of membrane CD64 and HLA-DR expression by blood neutrophils and monocytes using the monoclonal antibody fluorescence capability of a routine haematology analyser

This study reports the design of an immunofluorescent method for the co-determination of neutrophil CD64 (PMN-CD64), monocyte CD64 (MON-CD64) and monocyte HLA-DR (MON-Ia) expression with the Cell-Dyn CD4,000 haematology analyser. Normal PMN-CD64, MON-CD64 and MON-Ia expression, defined as the mean+/-2SD of 25 healthy adults after correction for isotype control staining, corresponded to 17-67, 515-1045 and 170-670 AFU respectively. Analytical reproducibility determined by duplicate analysis of 12 random samples revealed good assay consistency for all three analysed antigens, with day to day variation in normal subjects being relatively minor in significance. CD4,000 PMN-CD64 and HLA-DR values showed good inter-method correlation with flow cytometry although short term (12 h) stability studies suggested an in vitro trend for increasing PMN-CD64 and variable HLA-DR antigen expression with progressive storage. Observed ranges of PMN-CD64, MON-CD64 and MON-Ia for 109 randomly-selected clinical samples were 31-1058, 307-2843 and 10-876 AFU. Abnormal PMN-CD64 and MON-CD64 shared the same trend (upregulation) while abnormal monocyte MON-Ia was characterised by declining expression. Normal PMN-CD64 was only seen with normal (45/52) or intermediate (7/52) MON-CD64, while high PMN-CD64 was mostly associated with intermediate (18/22) or high (3/22) MON-CD64. MON-Ia expression was largely independent (p=0.04) of PMN-CD64 although marked decreases in MON-Ia were invariably associated with intermediate or high PMN-CD64. MON-Ia expression was inversely related (p<0.0001) to absolute granulocyte counts, and patients with high PMN-CD64 were more likely (8/25) to have in excess of 10% Band Cells compared to samples with normal/intermediate PMN-CD64 (0/84). When compared to C-reactive protein (CRP), high PMN-CD64 and MON-CD64 were always associated with an increased CRP concentration, but minor proportions of samples with normal PMN-CD64 (11/52) or normal MON-CD64 (11/65) could also have an increased CRP. The procedures described in this communication overcome a number of limitations associated with flow cytometry, and co-determination of CD64 and HLA-DR antigen expression may provide complimentary insights into patient heterogeneity in the assessment of suspected sepsis compared to CD64 analysis alone.

Cellular inflammatory response to persistent localized Staphylococcus aureus infection: phenotypical and functional characterization of polymorphonuclear neutrophils (PMN)

Persistent, localized Staphylococcus aureus infections, refractory to antibiotic treatment, can result in massive tissue destruction and surgical intervention is often the only therapeutic option. In that context, we investigated patients with S. aureus-induced infection at various sites, apparent as either olecranon bursitis, empyema of the knee joint or soft tissue abscess formation. As expected, a prominent leucocyte infiltrate was found, consisting predominantly of polymorphonuclear neutrophils (PMN) (up to 75%) and to a lesser extent of T lymphocytes and natural killer (NK) cells. In line with their bactericidal capacity, PMN expressed the high-affinity receptor for IgG, CD64 and the lipopolysaccharide (LPS) receptor CD14; moreover, the oxygen radical production in response to the bacterial peptide f-MLP was enhanced, while chemotactic activity was greatly reduced. The more intriguing finding, however, was that a portion of PMN had acquired major histocompatibility complex (MHC) class II antigens and CD83, indicative of a transdifferentiation of PMN to cells with dendritic-like characteristics. Of note is that a similar transdifferentiation can be induced in PMN in vitro, e.g. by gamma interferon or by tumour necrosis factor alpha. Co-cultivation of transdifferentiated PMN with autologous T lymphocytes resulted in prominent T cell proliferation, provided that S. aureus enterotoxin A was added. Taken together, persistent S. aureus infection induces PMN to acquire characteristics of dendritic cells, which in turn might promote the local immune response.