Neutrophil CD64 expression, procalcitonin and presepsin are useful to differentiate infections from flares in SLE patients with SIRS

Neutrophil Z Is a Novel Marker to Differentiate Disease Flares From Bacterial Infections in Febrile SLE Patients

AIM AND OBJECTIVES

To assess the role of newer biomarkers like neutrophil Z, myeloid-related protein 8/14 (MRP 8/14), IL-6, sCD14, and neutrophil CD64 (nCD64) to distinguish flare from infection in febrile lupus patients.

METHODS

In this prospective multicentric observational study to determine the etiology of fever in febrile lupus patients, in addition to routine tests, serum procalcitonin, neutrophil X, neutrophil Y, and neutrophil Z were done. sCD14, MRP8/14, and IL-6 were done by ELISA. nCD64 expression was measured by flow cytometry. All these biomarkers were assessed individually and in combination to see their ability to distinguish between infection and lupus flare.

RESULTS

Among 159 febrile SLE patients, there were 55 infections, 65 disease flares, 38 flares and infections combined, and 1 malignancy. Patients with bacterial infections had a higher CRP, procalcitonin, neutrophil-to-lymphocyte ratio, Neutrophil Z, sCD14 levels, and neutrophil CD64 expression. While patients with flares had lower C3, C4, and higher anti-DsDNA antibody levels. IL-6 and MRP8/14 levels were similar in both groups. Combination of neut-Z with C3 or anti-dsDNA antibody could discriminate between flare and infection with AUC 0.88 (0.80-0.96) and 0.86 (0.78-0.95). Addition of TLC or procalcitonin or nCD64 MFI to these scores improved them marginally. Though composite scores with CRP and anti-dsDNA/procalcitonin also performed well but these were inferior to neutrophil Z-based composite models. These results were consistent in sensitivity analysis.

CONCLUSION

Neutrophil Z, complement C3, anti-dsDNA antibody levels, and TLC or procalcitonin-based composite score are good tools to differentiate between infection and flare in a febrile lupus patient. Serum MRP 8/14, IL-6, sCD14, and nCD64 did not perform well. Simple biomarkers such as neut-Z should be investigated further in SLE.

Infection versus disease activity in systemic lupus erythematosus patients with fever

BACKGROUND

to detect the role of procalcitonin, erythrocyte sedimentation rate to c-reactive protein (ESR/CRP) ratio, neutrophils-to-lymphocyte ratio (NLR), and platelets-to-lymphocyte ratio (PLR) in the diagnosis of infection in systemic lupus erythematosus (SLE) patients with fever, their diagnostic value to differentiate between infection and disease activity, and their correlation with disease activity.

METHODS

Forty SLE patients and forty healthy control cases were included in the study. Disease activity was assessed by the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2 K), and quality of life was assessed by Lupus QoL. A bacterial infection was detected by clinical symptoms and positive culture results. Laboratory tests were done for all patients and controls: complete blood count (CBC), ESR, CRP, and procalcitonin (PCT). NLR, PLR, and ESR/CRP ratios were calculated.

RESULTS

There was a statistically significant difference between infected SLE patients and non-infected SLE patients regarding PCT (p < 0.001), ESR (p = 0.002), CRP (p = 0.005), ESR/CRP ratio (0.002), and NLR (p = 0.023). PCT, ESR, CRP, and NLR were positively correlated with the presence of infection in SLE patients, while the ESR/CRP ratio was negatively correlated. There was no significant correlation with the SLEDAI-2 K score. Logistic regression analysis revealed that PCT was the best significant predictor of infection (OR 224.37, 95% CI 8.94-5631.35). PCT was a good predictor of infection, with a cut-off value of 0.90 ng/ml, which gave the best combination of sensitivity (84.62%) and specificity (85.71%).

CONCLUSION

PCT, ESR/CRP ratio, and NLR provide good diagnostic markers for the diagnosis of infection and can distinguish between infection and disease flare in SLE patients with fever.

T lymphocyte subsets and immunoglobulin and complement levels are associated with the infection status of patients with antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND

Infection is the leading cause of death in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). The aim of this study was to characterize the immunological features of infectious events occurring in patients with newly diagnosed AAV and to identify possible risk factors associated with infection.

METHODS

The T lymphocyte subsets, immunoglobulin, and complement levels of the groups were compared between infected group and the noninfected group. Further, regression analysis was conducted to determine the association of each variable with the risk of infection.

RESULTS

280 patients with newly diagnosed AAV were enrolled. The average levels of CD3+ T cells (720.0 vs. 920.5, P < 0.001), CD3+CD4+ T cells (392.0 vs. 547.0, P < 0.001), and CD3+CD8+ T cells (248.0 vs. 335.0, P = 0.001), serum IgG (11.66 g/L vs. 13.59 g/L, P = 0.002), IgA (1.70 g/L vs. 2.44 g/L, P < 0.001), C3 (1.03 g/L vs. 1.09 g/L, P = 0.015), and C4 (0.24 g/L vs. 0.27 g/L, P < 0.001) were significantly lower in the infected group than in the noninfected group. The levels of CD3+CD4+ T cells (adjusted OR 0.997, P = 0.018), IgG (adjusted OR 0.804, P = 0.004), and C4 (adjusted OR 0.001, P = 0.013) were found independently associated with infection.

CONCLUSIONS

Patients of infected AAV and those without infection differ in T lymphocyte subsets and immunoglobulin and complement levels. Furthermore, CD3+CD4+ T cells counts and serum IgG and C4 levels were independent risk factors with infection in patients with newly diagnosed AAV.

Differentiating flare and infection in febrile lupus patients: Derivation and validation of a calculator for resource constrained settings

Background: Patients with Systemic Lupus Erythematous (SLE) are at an increased risk of infection and it is often difficult to differentiate between infection and disease activity in a febrile patient with SLE. Methods: Patients with SLE (SLICC criteria) presenting with fever between December 2018 and August 2021 were included. Neutrophil to lymphocyte ratio (NLR), NEUT-x, -y, -z indices, Erythrocyte sedimentation rate (ESR), C-reactive protein(CRP), C3, C4, anti-dsDNA antibodies, and procalcitonin(PCT) were tested in addition to investigations as per the treating physician's discretion. Based on the clinical assessment and laboratory data, the febrile episode was classified into infection, disease flare, or both. Statistical analysis was done using GraphPad prism v8.4.2. A novel composite score was devised and validated with a calculator incorporated is a spreadsheet. The performance of a previously proposed model of duration of fever, CRP, and dsDNA (Beca et al) was evaluated and other models using PCT and NEUT-Z were explored. Results: Among 168 febrile episodes in 166 patients with SLE (25 (19-32) years), 46 were due to infection, 77 due to flare, 43 due to both, and two due to other causes. High SLEDAI 2K (0.001), anti-dsDNA (p = 0.004), and low complements(C3, p = 0.001 and C4, p = 0.001) were characteristic of disease flare, whereas high total leukocyte count (TLC) (p = 0.008), NLR (p = 0.008), NEUT-x (p = 0.001), -y (p = 0.03), -z (p = 0.002), CRP (p = 0.001), and PCT (p = 0.03) were observed with infection. A model using age, TLC, and CRP was devised using 80% of the cohort with an AUC of 0.88 (0.78-0.97) which was validated in the remaining 20% to have an AUC of 0.83(0.60-1.0). The model devised by Beca et al yielded an AUC of 0.74. Use of PCT did not improve the discrimination between flare and infection. A Model of C4 and NEUT-z analyzed in a subset performed well and needs further exploration. Conclusion: A composite score of low cost and routinely available parameters like age, TLC, and CRP gives a good discrimination between infection and flare in a febrile patient with SLE.

The utility of erythrocyte sedimentation rate, C-reactive protein, and procalcitonin in detecting infections in patients with systemic lupus erythematosus: A systematic review

OBJECTIVES

We conducted a systematic review with metanalysis to investigate the utility of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and procalcitonin (PCT) in diagnosing infections in hospitalized patients with SLE.

METHODS

We searched Medline, Embase, Web of Science, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials (CENTRAL) with a search strategy developed by a medical librarian. We included retrospective, cross-sectional, case-control, and prospective studies in our analysis. We used the Quality Assessment of Diagnostic Studies (QUADAS-2) to assess for bias and applicability. We obtained mean differences, sensitivities, and specificities in our analysis.

RESULTS

We included 26 studies in our analysis. Most studies had an unclear or high risk of bias and our results were widely heterogenous. For the diagnosis of infections, the CRP had a pooled sensitivity of 0.75 (95%CI 0.57-0.94) and specificity of 0.72 (0.59-0.85), PCT had a pooled sensitivity of 0.68 (95% CI 0.0.59-0.77) and specificity of 0.75 (0.59-0.90), and for ESR pooled estimates were not calculated but sensitivity ranged from 50 to 69.8 and specificity from 38.5 to 55.6. Modifying cut-offs improved sensitivities and specificities. The ESR, CRP, and PCT mean differences were all greater in infection groups versus non-infection (10.1, 95% CI 3.2-17.0; 46.8, 95% CI 36.5-57.0; 0.53, 95% CI 0.26-0.80; respectively).

DISCUSSION

Poor sensitivities and specificities were observed for the evaluated biomarkers with substantial heterogeneity in the cut-offs used to determine infection. Although mean biomarker values were increased in the infection group compared with the non-infection, our findings do not support the widespread use of ESR, CRP, or PCT in diagnosing infection in hospitalized patients with SLE due to increased heterogeneity and risk of bias. Further investigation is needed.

Performance of Procalcitonin to Distinguish Fungal from Bacterial Infections in Patients with Systemic Lupus Erythematosus

Purpose

To evaluate the performance of serum procalcitonin (PCT) concentrations to diagnose fungal infection in patients with systemic lupus erythematosus (SLE).

Patients and Methods

From January 2017 to October 2020, SLE patients hospitalized for serious infection with an identified single bacterial or fungal pathogen, as well as PCT measured within 24h after admission were included. The diagnostic performance of PCT was evaluated independently and in combination with the white blood cell (WBC) count, C-reactive protein (CRP) level, and erythrocyte sedimentation rate (ESR). The analysis included the sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, and the crude and adjusted area under the receiver operating characteristic curve (AUROC).

Results

Sixty-nine patients were included; 26 had a fungal infection (38%) and 43 had a bacterial infection (22 gram-positive and 21 gram-negative). Fungal infection patients were mainly distributed in the respiratory group (88.5%), and bacterial infection distribution were more prevalent in respiratory group (44.2%) and abdominal/urinary group (23.3%). The PCT concentration was significantly lower in fungal infections than bacterial infections (fungal: 0.22 ng/mL, interquartile range [IQR], 0.09-0.44 vs bacterial: 0.60 ng/mL, IQR, 0.16-5.74; p = 0.016) and differed significantly between different infection sites (p = 0.022). PCT had better diagnostic performance for predicting fungal infection (AUROC = 0.731) than the WBC count (AUROC = 0.581), the CRP level (AUROC = 0.716), and ESR (AUROC = 0.583). PCT and ESR together had the best diagnostic performance, with 46.2% sensitivity and 88.4% specificity. Further, the AUROC increased compared to PCT alone but was statistically insignificant (p = 0.693).

Conclusion

For SLE patients with serious infection, the PCT concentration had better diagnostic accuracy for predicting fungal infection than the WBC count, the CRP level, and ESR. Combining PCT and ESR obtained the highest AUROC and provided an acceptable discrimination performance.

Development of Prediction Models for New Integrated Models and a Bioscore System to Identify Bacterial Infections in Systemic Lupus Erythematosus

Objectives

Distinguishing flares from bacterial infections in systemic lupus erythematosus (SLE) patients remains a challenge. This study aimed to build a model, using multiple blood cells and plasma indicators, to improve the identification of bacterial infections in SLE.

Design

Building PLS-DA/OPLS-DA models and a bioscore system to distinguish bacterial infections from lupus flares in SLE.

Setting

Department of Rheumatology of the Second Hospital of Shanxi Medical University.

Participants

SLE patients with flares (n = 142) or bacterial infections (n = 106) were recruited in this retrospective study.

Outcome

The peripheral blood of these patients was collected by the experimenter to measure the levels of routine examination indicators, immune cells, and cytokines. PLS-DA/OPLS-DA models and a bioscore system were established.

Results

Both PLS-DA (R2Y = 0.953, Q2 = 0.931) and OPLS-DA (R2Y = 0.953, Q2 = 0.942) models could clearly identify bacterial infections in SLE. The white blood cell (WBC), neutrophile granulocyte (NEUT), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), IL-10, interferon-γ (IFN-γ), and tumor necrosis factor α (TNF-α) levels were significantly higher in bacteria-infected patients, while regulatory T (Treg) cells obviously decreased. A multivariate analysis using the above 10 dichotomized indicators, based on the cut-off value of their respective ROC curve, was established to screen out the independent predictors and calculate their weights to build a bioscore system, which exhibited a strong diagnosis ability (AUC = 0.842, 95% CI 0.794–0.891). The bioscore system showed that 0 and 100% of SLE patients with scores of 0 and 8–10, respectively, were infected with bacteria. The higher the score, the greater the likelihood of bacterial infections in SLE.

Conclusions

The PLS-DA/OPLS-DA models, including the above biomarkers, showed a strong predictive ability for bacterial infections in SLE. Combining WBC, NEUT, CRP, PCT, IL-6, and IFN-γ in a bioscore system may result in faster prediction of bacterial infections in SLE and may guide toward a more appropriate, timely treatment for SLE.

Evaluation of serum presepsin, procalcitonin, copeptin, and high-sensitivity C-reactive protein for differentiating bacterial infection from disease activity in Egyptian patients with systemic lupus erythematosus

OBJECTIVES

Several biological markers have been studied for the differentiation of infection from disease activity in systemic lupus erythematosus (SLE) patients with discrepant results. We aimed to evaluate the role of serum presepsin, hs-CRP, procalcitonin (PCT), and copeptin (CPP) in differentiating bacterial infections from disease activity in SLE patients.

METHODS

This study is a cross-sectional observational study in which 94 Egyptian patients were recruited from June 2017 to January 2018. Our patients were divided into two groups: group (1) included 48 patients with active SLE hospitalized with any sort of lupus activity and group (2) included 46 patients with active SLE admitted with a proven bacterial infection. Hs-CRP, presepsin, PCT, and CPP were measured using enzyme-linked immune sorbent assay technique.

RESULTS

Hs-CRP, presepsin, PCT, and CPP were highly significantly higher among group (2) patients compared to group (1) patients (p < 0.001). Serum presepsin expressed higher specificity than hs-CRP (87.5% vs 60.4%) but the same sensitivity (80.4%) in the detection of bacterial infection in SLE patients. Serum PCT expressed higher specificity than hs-CRP (100% vs 60.4%) but lower sensitivity (73.9% vs 80.4%). Serum CPP expressed higher specificity than hs-CRP (65.9% vs 60.4%) but lower sensitivity (65.9% vs 80.4%).

CONCLUSION

Our study suggests that increased serum levels of hs-CRP, presepsin and PCT levels are useful in differentiating bacterial infections from disease activity in SLE patients. Serum CPP could be used as an adjunct with more specific inflammatory biomarkers in making better diagnostic judgments.

KEY POINTS

• The increased serum levels of hs-CRP, presepsin and PCT levels are useful in differentiating bacterial infections from disease activity in SLE patients. • Serum Presepsin expressed higher specificity than hs-CRP but the same sensitivity in the detection of bacterial infection in SLE patients. • Serum CPP expressed higher specificity than hs-CRP but lower sensitivity.

Infections in hospitalized children with newly diagnosed systemic lupus erythematosus in underresourced areas

Background

The administration of induction immunosuppressive therapy to children with newly diagnosed systemic lupus erythematosus (SLE) and concurrent infections can lead to unfavourable outcomes. This study was conducted to describe characteristics of infections occurring before the initiation of immunosuppressants in hospitalized children with newly diagnosed SLE in underresourced areas.

Methods

Medical records of paediatric patients with the diagnosis of SLE, who were admitted to a university-based hospital from 2002 to 2018, were reviewed. Only patients younger than 18 years of age with newly diagnosed SLE were included in the study. The primary outcome was infection before the administration of immunosuppressants. Logistic regression analysis was used to determine factors associated with infection and adjusted odds ratio (OR). The diagnostic accuracy of CRP was assessed.

Results

Infections were confirmed in 52/124 (41.9%) children. Pathogens were identified in 24 (46.2%) patients with bacterial predominance. The most common site was respiratory infections (36.5%). Fever and serosal involvement were more prevalent in patients with infection. Serum CRP levels were significantly higher in patients with infection than in those without infection (median 5.5 mg/L (interquartile range (IQR) 3.6–76.3 mg/L) vs. 3.5 mg/L (IQR 3.0–3.6 mg/L), p = 0.004). When a positive CRP level of >5 mg/L was used, positive CRP was found with a higher prevalence in patients with infection and was independently associated with infection (adjusted odds ratio (OR) = 28.6, 95% confidence interval (CI) 2.3–350.6; p = 0.009). Patients with infection had a longer hospital stay than patients without infection (median 20 days (IQR 13–25 days) vs. 15 days (IQR 9–24 days), p = 0.04). Sensitivity, specificity, positive predictive value and negative predictive value with 95% CI of CRP >5 mg/L were 62.5% (35.4–84.8%), 88.9% (65.3–98.6%), 80.3% (51.0–94.1%) and 76.6% (63.1–86.3%), respectively.

Conclusions

Infections were common among hospitalized children with newly diagnosed SLE. Children with infections had a prolonged course of hospitalization. Positive CRP was associated with a predisposition towards infection. However, the diagnostic accuracy of CRP requires further validation in a larger study.

Clinical application of presepsin as diagnostic biomarker of infection: overview and updates

The appropriate identification of bacterial infection is the basis for effective treatment and control of infective disease. Among this context, an emerging biomarker of infection is presepsin (PSP), recently described as early marker of different infections. PSP secretion has been shown to be associated with monocyte phagocytosis and plasmatic levels of PSP increase in response to bacterial infection and decrease after antibiotic treatment, therefore it can be considered a marker of activation of immune cell response towards an invading pathogen. Different methods have been developed to measure PSP and this review will briefly describe the different clinical fields of application of PSP, ranging from intensive care to neonatal infection, to orthopedic and pulmonary infection as well as fungal infections and cardiovascular infections.

Complement, infection, and autoimmunity

PURPOSE OF REVIEW

Complement system dysfunction in terms of upregulation, downregulation, or dysregulation can create an imbalance of both host defense and inflammatory response leading to autoimmunity. In this review, we aimed at describing the role of complement system in host defense to inflection and in autoimmunity starting from the evidence from primary and secondary complement system deficiencies.

RECENT FINDINGS

Complement system has a determinant role in defense against infections: deficiencies of complement components are associated with increased susceptibility to infections. Primary complement system deficiencies are rare disorders that predispose to both infections and autoimmune diseases. Secondary complement system deficiencies are the result of the complement system activation with consumption. Complement system role in enhancing risk of infective diseases in secondary deficiencies has been demonstrated in patients affected by systemic autoimmune disorders, mainly systemic lupus erythematosus and vasculitis.

SUMMARY

The relationship between the complement system and autoimmunity appears paradoxical as both the deficiency and the activation contribute to inducing autoimmune diseases. In these conditions, the presence of complement deposition in affected tissues, decreased levels of complement proteins, and high levels of complement activation fragments in the blood and vessels have been documented.

[Acute exacerbation of the underlying disease or infection : Which diagnostics are warranted in patients with immunosuppressive treatment for inflammatory rheumatic diseases?]

Infectious diseases always have to be considered in the differential diagnosis of new symptoms in patients with immunosuppressive treatment for established inflammatory rheumatic diseases. Knowledge about the specific frequency and type of infections that can be expected under immunosuppressive treatment of inflammatory rheumatic diseases as well as the diagnostic value of laboratory tests and imaging results can facilitate the often difficult differential diagnosis.

Risk factors of infection-associated mortality in children with lupus nephritis in under-resourced areas

INTRODUCTION

Treatment of lupus nephritis class III, IV and V with immunosuppressive therapy increases patient survival but poses a risk of infection-related mortality. This study was conducted to evaluate risk factors for fatal infection in children with lupus nephritis in under-resourced areas.

METHODS

Medical records of patients, who were admitted to a tertiary-care university-based hospital from January 2002 to July 2018 with the diagnosis of systemic lupus erythematosus, were reviewed. Only patients aged less than 18 years with lupus nephritis and documented infection were included in the study. The primary outcome was infection-associated mortality. The logistic regression model was used to identify independent variables associated with fatal infection. Predicted probabilities of infection-related mortality adjusted for factors significant in multivariate analysis were calculated using marginal effects at representative values.

RESULTS

Infection-related deaths occurred in 27 of 179 patients (15.1%). Hospital-acquired infections occurred in 72 of 375 episodes of hospital admissions (19.2%) and 13 hospital-acquired infections (18.1%) resulted in fatal infection. Invasive fungal infections were the leading cause of death (44.4%) and pulmonary infections were the predominant site (55.5%). Haemoglobin levels and glomerular filtration rates were significantly lower in deceased versus surviving patients. Percentages of patients with hospital-acquired infections, invasive fungal infections and pulmonary infections were significantly higher in deceased than surviving patients. Urine protein, the neutrophil-to-lymphocyte ratio, cumulative methylprednisolone dose and daily prednisolone dose were significantly higher in deceased than surviving patients. In multivariate analysis, a neutrophil-to-lymphocyte ratio more than 20, invasive fungal infections and high daily prednisolone dose were independently predictive of fatal infection with adjusted odds ratio of 3.02 (95% confidence interval 1.02-8.97, p = 0.04), 15.08 (95% confidence interval 4.72-48.24, p < 0.001) and 1.03 (95% confidence interval 1.01-1.06, p = 0.04), respectively. A high daily prednisolone dose intensified the impact of invasive fungal infections and high neutrophil-to-lymphocyte ratio on predicted probability of infection-associated mortality.

CONCLUSIONS

Prevention of invasive fungal infections and minimization of daily prednisolone should be emphasized in routine clinical practice of children with lupus nephritis in under-resourced areas to achieve better survival. Children with lupus nephritis and a high neutrophil-to-lymphocyte ratio should be under cautious surveillance for infection.

Role of biomarkers in the diagnosis of bacterial infections in rheumatic diseases

In modern rheumatology, the problem of differential diagnosis of bacterial infection and active rheumatic process still retains its relevance. At the same time, it is very important to search for a biomarker - the gold standard for the diagnosis of an infection in patients with rheumatic diseases (RDs) in order to rapidly determine a treatment policy. This review analyzes the diagnostic significance and possibility of using some laboratory markers for bacterial infections in modern rheumatology. It emphasizes the importance of a multimarker approach that allows increasing the significance of individual parameters in the diagnosis of infections in RD.

Altered peripheral lymphocyte subsets in untreated systemic lupus erythematosus patients with infections

The leading cause of death in systemic lupus erythematosus (SLE) patients is infection. The objective of this study was to evaluate the distribution of lymphocyte subsets in untreated SLE patients with infections. This was a cross-sectional study. Data from January 2017 to May 2018 were collected. Flow cytometry was used to measure the peripheral lymphocyte subsets including CD3+T cells, CD4+T cells, CD8+T cells, CD19+B cells, CD3-CD16+CD56NK cells, and CD3+CD16+CD56NKT cells in 25 healthy controls and 52 treatment-naive SLE patients, among whom 13 were complicated with infections. Association between the lymphocyte subsets and infections was further analyzed. SLE patients with infections (n=13) showed a significantly higher incidence rate of fever (84.6 vs 28.2%) and serositis (84.6 vs 23.1%), increased level of erythrocyte sedimentation rate (60.5±30.1 vs 37.4±27.1 mm/h), serum C-reactive protein (CRP) (102.7±94.9 vs 9.4±14.9 mg/L), procalcitonin (PCT) (1.07±0.08 vs 0.16±0.13 μg/L), and lower blood hemoglobin (Hb) (93.0±20.5 vs 110.4±16.0 g/L) level compared with non-infection patients (n=39) (all P<0.05). In comparison with non-infectious SLE patients (387.9±261.6/μL), CD4+T cells count decreased significantly in infectious SLE patients (217.8±150.4/μL) (P<0.05), and it was negatively correlated with infection-related indicators including PCT (r=-0.573, P=0.041) and CRP (r=-0.596, P=0.032) levels. Our findings suggested that abnormalities of peripheral lymphocyte subsets were related to the immune disorder of lupus itself, regardless of immunosuppressive treatment. Monitoring lymphocyte subsets, especially CD4+T cells, may be helpful for identifying the presence of infection in SLE patients.

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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