Repeated iv anti-CD20 treatment in multiple sclerosis: Long-term effects on peripheral immune cell subsets.

OBJECTIVE: Repeated intravenous administration of anti-CD20 depleting monoclonal antibodies 6 months apart is among the highly effective treatment options in multiple sclerosis (MS). Here, we aimed to investigate peripheral immune cell subset depletion kinetics following either rituximab (RTX) or ocrelizumab (OCR) infusions in people with MS (pwMS). METHODS: We studied pwMS treated de-novo with either RTX (n = 7) or OCR (n = 8). The examinations were scheduled before the initiation of anti-CD20 therapy and every 12 weeks for up to 15 months. Immunophenotyping of immune cell subsets in peripheral blood was performed by multiparametric fluorescence cytometry. RESULTS: A significant, persistent decrease of CD19+ B cells was observed already with the first anti-CD20 infusion (p < 0.0001). A significant proportional reduction of memory B cells within the B-cell pool was achieved only after two treatment cycles (p = 0.005). We observed a proportional increase of immature (p = 0.04) and naive B cells (p = 0.004), again only after the second treatment cycle. As for the peripheral T-cell pool, we observed a continuous proportional increase of memory T helper (TH) cells/central memory TH cells (p = 0.02/p = 0.008), while the number of regulatory T cells (Treg) decreased (p = 0.007). The percentage of B-cell dependent TH17.1 central memory cells dropped after the second treatment cycle (p = 0.02). No significant differences in the depletion kinetics between RTX and OCR were found. INTERPRETATION: Peripheral immune cell profiling revealed more differentiated insights into the prompt and delayed immunological effects of repeated intravenous anti-CD20 treatment. The observation of proportional changes of some pathogenetically relevant immune cell subsets only after two infusion cycles deserves further attention.

Diagnostic Workup of Microcytic Anemia: An Evaluation of Underuse or Misuse of Laboratory Testing in a Hospital Setting Using the AlinIQ System.

CONTEXT.­: Underuse of laboratory testing has been previously investigated in preselected populations, such as documented malpractice claims. However, these numbers might not reflect real-life situations. OBJECTIVE.­: To evaluate the underuse and misuse of laboratory follow-up testing in a real-life hospital patient population with microcytic anemia, using laboratory results ordered during routine patient care. DESIGN.­: From all patients in whom a microcytic anemia was detected during routine diagnostics in 2018, all available laboratory data were collected and screened for appropriateness of diagnostic workup of iron deficiency and thalassemia. Subgroup analysis was performed for patient groups with mean corpuscular volume values 75 to 79 µm3 (group 1), 65 to 74 µm3 (group 2), and <65 µm3 (group 3). RESULTS.­: A total of 2244 patients with microcytic anemia were identified. Follow-up testing for iron deficiency was not performed in 761 cases (34%). For inconclusive ferritin levels due to elevated C-reactive protein results (n = 336), reticulocyte hemoglobin content or soluble transferrin receptor levels were missing in 86 cases (26%). In patients with suspected thalassemia (n = 127), follow-up testing for hemoglobin variants was not performed in 70 cases (55%). Subgroup analysis showed that the frequency of underuse of iron status as well as thalassemia/hemoglobinopathy testing decreased from group 1 to group 3. When considering relevant preexisting anemia diagnoses, laboratory tests were underused in 904 cases (40.3%). CONCLUSIONS.­: Because 40% (n = 904) of the patients with microcytic anemia were potentially not followed up correctly, laboratory specialists are advised to act by implementing demand management strategies in collaboration with clinicians to overcome underuse of laboratory tests and to improve patient safety.

Efficiency, efficacy and subjective user satisfaction of alternative laboratory report formats. An investigation on behalf of the Working Group for Postanalytical Phase (WG-POST), of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM).

OBJECTIVES: Although laboratory result presentation may lead to information overload and subsequent missed or delayed diagnosis, little has been done in the past to improve this post-analytical issue. We aimed to investigate the efficiency, efficacy and user satisfaction of alternative report formats. METHODS: We redesigned cumulative (sparkline format) and single reports (improved tabular and z-log format) and tested these on 46 physicians, nurses and medical students in comparison to the classical tabular formats, by asking standardized questions on general items on the reports as well as on suspected diagnosis and follow-up treatment or diagnostics. RESULTS: Efficacy remained at a very high level both in the new formats as well as in the classical formats. We found no significant difference in any of the groups. Efficiency improved in all groups when using the sparkline cumulative format and marginally when showing the improved tabular format. When asking medical questions, efficiency and efficacy remained similar between report formats and groups. All alternative reports were subjectively more attractive to the majority of participants. CONCLUSIONS: Showing cumulative reports as a graphical display led to faster detection of general information on the report with the same level of correctness. Considering the familiarity bias of the classical single report formats, the borderline-significant improvement of the alternative tabular format and the non-inferiority of the z-log format, suggests that single reports might benefit from some improvements derived from basic information design.

Acidification of 24-hour urine in urolithiasis risk testing: An obsolete relic?

BACKGROUND: Recommendations on the optimal preservation of 24 h urine for the metabolic work-up in urolithiasis patients are very heterogeneous. In case two such tests with different storage condition recommendations are being analysed, multiple collections would be needed, challenging especially elderly and very young patients. We therefore aimed to evaluate the stability of urine constituents under different storage conditions. MATERIAL AND METHODS: We collected urine samples from ten healthy volunteers and prepared aliquots to be stored either at room temperature or 4 °C. Some aliquots were preserved using hydrochloric acid prior to storage, some thereafter, some using the BD Urine preservation tube and some were not preserved at all. Storage duration was 0, 24, 48 or 72 h. In all samples calcium, magnesium, phosphorus, creatinine, oxalate, citrate and uric acid were measured and compared to the according reference sample. RESULTS: We could not find any significant deviation for any of the analytes and preanalytical treatment conditions compared to the associated reference sample. CONCLUSION: Preservation of 24 h urine for the metabolic evaluation in stone formers might not be necessary for sample storage up to 72 h.

Long-term immunological consequences of anti-CD20 therapies on humoral responses to COVID-19 vaccines in multiple sclerosis: an observational study.

Background: Anti-CD20 therapies induce pronounced B-cell depletion and blunt humoral responses to vaccines. Recovery kinetics of anti-CD20 therapy-mediated cellular and humoral effects in people with multiple sclerosis (pwMS) are poorly defined. Objective: To investigate the duration of the anti-CD20 treatment-induced effects on humoral responses to COVID-19 vaccines. Methods: This retrospective observational study included pwMS who had discontinued anti-CD20 therapy for ⩾12 months and remained without immunomodulation. We retrieved demographics and laboratory parameters including B-cell counts and immunoglobulin (IgG, IgM, IgA) levels prior to anti-CD20 commencement (baseline) and longitudinally after anti-CD20 treatment discontinuation from electronic medical records. Humoral responses to SARS-CoV-2 vaccines were compared with a population of 11 pwMS with ongoing anti-CD20 medication (control cohort). Results: A total of 24 pwMS had discontinued anti-CD20 therapy for a median of 34 months (range: 16-38 months). Antibody responses to COVID-19 vaccines were available in 17 (71%). Most individuals (n = 15, 88%) elicited a measurable antibody response [mean: 774 BAU/ml (±SD 1283 BAU/ml)] to SARS-CoV-2 immunization on average 22 months (range: 10-30 months) from the last anti-CD20 infusion, which was higher compared with the population with ongoing anti-CD20 therapy (n = 11, mean: 12.36 ± SD 11.94 BAU/ml; p < 0.00001). Significantly increased antibody levels compared with the control cohort were found among pwMS who were vaccinated >18 months after treatment discontinuation (19-24 months: n = 2, p = 0.013; 25-36 months: n = 9; p < 0.001). The interindividual kinetics for B-cell reconstitution were heterogeneous and mean B-cell counts approached normal ranges 18 months after treatment discontinuation. There was no correlation of B-cell repopulation and vaccine responses. Mean total IgG, IgM, and IgA levels remained within the reference range. Conclusion: Anti-CD20-induced inhibition of humoral responses to COVID-19 vaccines is transient and antibody production was more pronounced >18 months after anti-CD20 treatment discontinuation. The immunological effect on B-cell counts appears to wane by the same time.

Cladribine Alters Immune Cell Surface Molecules for Adhesion and Costimulation: Further Insights to the Mode of Action in Multiple Sclerosis.

Cladribine (CLAD) is a deoxyadenosine analogue prodrug which is given in multiple sclerosis (MS) as two short oral treatment courses 12 months apart. Reconstitution of adaptive immune function following selective immune cell depletion is the presumed mode of action. In this exploratory study, we investigated the impact of CLAD tablets on immune cell surface molecules for adhesion (CAMs) and costimulation (CoSs) in people with MS (pwMS). We studied 18 pwMS who started treatment with CLAD and 10 healthy controls (HCs). Peripheral blood mononuclear cells were collected at baseline and every 3 months throughout a 24-month period. We analysed ICAM-1, LFA-1, CD28, HLADR, CD154, CD44, VLA-4 (CD49d/CD29), PSGL-1 and PD-1 with regard to their expression on B and T cells (T helper (Th) and cytotoxic T cells (cT)) and surface density (mean fluorescence intensity, MFI) by flow cytometry. The targeted analysis of CAM and CoS on the surface of immune cells in pwMS revealed a higher percentage of ICAM-1 (B cells, Th, cT), LFA-1 (B cells, cT), HLADR (B cells, cT), CD28 (cT) and CD154 (Th). In pwMS, we found lower frequencies of Th and cT cells expressing PSGL-1 and B cells for the inhibitory signal PD-1, whereas the surface expression of LFA-1 on cT and of HLADR on B cells was denser. Twenty-four months after the first CLAD cycle, the frequencies of B cells expressing CD44, CD29 and CD49d were lower compared with the baseline, together with decreased densities of ICAM-1, CD44 and HLADR. The rate of CD154 expressing Th cells dropped at 12 months. For cT, no changes were seen for frequency or density. Immune reconstitution by oral CLAD was associated with modification of the pro-migratory and -inflammatory surface patterns of CAMs and CoSs in immune cell subsets. This observation pertains primarily to B cells, which are key cells underlying MS pathogenesis.

Pre-Existing Humoral Immunological Memory Is Retained in Patients with Multiple Sclerosis Receiving Cladribine Therapy.

Cladribine (CLAD) is a lymphodepleting agent approved for active relapsing multiple sclerosis (MS). The impact of CLAD on the adaptive humoral immune system has not sufficiently been studied. This study aimed to assess the influence of CLAD treatment on specific antibody titers to common pathogens. We included 18 MS patients treated with CLAD. Serum IgG antibody levels to measles, mumps, rubella, hepatitis B and varicella zoster virus (VZV), as well as diphtheria and tetanus toxins, were measured prior to the initiation of treatment and at 12 and 24 months after first CLAD administration. Moreover, specimens were longitudinally analyzed regarding absolute blood concentrations of IgG and main lymphocyte subsets. No reduction in antibody levels against measles, mumps, rubella, VZV, hepatitis B, diphtheria toxin and tetanus toxin associated with CLAD treatment was observed. Loss of seroprotection occurred in <1%. We found no significant impact of CLAD on absolute serum IgG levels. Absolute lymphocyte counts were significantly reduced at the end of each treatment year (p < 0.00001 and p < 0.000001). This study suggests that CLAD does not interfere with the pre-existing humoral immunologic memory in terms of pathogen-specific antibody titers.

Tetravalent Influenza Vaccine Is Not Associated With Neuroaxonal Damage in Multiple Sclerosis Patients.

Background: Efficacy of vaccines and disease activity linked to immunization are major concerns among people with multiple sclerosis (pwMS). Objective: To assess antibody responses to seasonal influenza antigens and vaccine-associated neuroaxonal damage utilizing serum neurofilament light chain (sNfL) in pwMS receiving dimethyl fumarate (DMF). Methods: In this prospective study, the 2020/2021 seasonal tetravalent influenza vaccine was administered to 20 pwMS treated with DMF and 15 healthy controls (HCs). The primary endpoints were responder rate of strain-specific antibody production (seroconversion or significant (4-fold) increase in influenza-antibody titers for ≥2/4 strains) at 30 days post-vaccination and changes in sNfL levels. Results: All patients treated with DMF fulfilled the responder criteria for immunization compared with 53% of the controls. However, higher proportions of HCs already had influenza-antibody titers ≥1:40 at baseline (53% vs. 41%, p = 0.174). sNfL levels were comparable among both groups at baseline and did not increase 34 days after vaccination. In addition, no clinical or radiological disease reactivation was found. Conclusion: DMF-treated patients mount an adequate humoral immune response to influenza vaccines. Within the limits of the small cohort investigated, our data suggest that influenza immunization is not associated with clinical or subclinical disease reactivation.

The CXCL13/CXCR5-chemokine axis in neuroinflammation: evidence of CXCR5+CD4 T cell recruitment to CSF.

BACKGROUND: C-X-C chemokine ligand 13 (CXCL13) is frequently elevated in cerebrospinal fluid (CSF) in a variety of inflammatory central nervous system (CNS) diseases, has been detected in meningeal B cell aggregates in brain tissues of multiple sclerosis patients, and proposedly recruits B cells into the inflamed CNS. Besides B cells also follicular helper T (Tfh) cells express the cognate receptor C-X-C chemokine receptor type 5 (CXCR5) and follow CXCL13 gradients in lymphoid tissues. These highly specialized B cell helper T cells are indispensable for B cell responses to infection and vaccination and involved in autoimmune diseases. Phenotypically and functionally related circulating CXCR5+CD4 T cells occur in blood. Their co-recruitment to the inflamed CSF is feasible but unresolved. METHODS: We approached this question with a retrospective study including data of all patients between 2017 and 2019 of whom immune phenotyping data of CXCR5 expression and CSF CXCL13 concentrations were available. Discharge diagnoses and CSF laboratory parameters were retrieved from records. Patients were categorized as pyogenic/aseptic meningoencephalitis (ME, n = 29), neuroimmunological diseases (NIMM, n = 22), and non-inflammatory neurological diseases (NIND, n = 6). ANOVA models and Spearman's Rank-Order correlation were used for group comparisons and associations of CXCL13 levels with immune phenotyping data. RESULTS: In fact, intrathecal CXCL13 elevations strongly correlated with CXCR5+CD4 T cell frequencies in the total cohort (p < 0.0001, r = 0.59), and ME (p = 0.003, r = 0.54) and NIMM (p = 0.043, r = 0.44) patients. Moreover, the ratio of CSF-to-peripheral blood (CSF/PB) frequencies of CXCR5+CD4 T cells strongly correlated with CXCL13 levels both in the total cohort (p = 0.001, r = 0.45) and ME subgroup (p = 0.005, r = 0.50), indicating selective accumulation. ME, NIMM and NIND groups differed with regard to CSF cell counts, albumin quotient, intrathecal IgG, CXCL13 elevations and CXCR5+CD4 T cells, which were higher in inflammatory subgroups. CONCLUSION: The observed link between intrathecal CXCL13 elevations and CXCR5+CD4 T cell frequencies does not prove but suggests recruitment of possible professional B cell helpers to the inflamed CSF. This highlights CSF CXCR5+CD4 T cells a key target and potential missing link to the poorly understood phenomenon of intrathecal B cell and antibody responses with relevance for infection control, chronic inflammation and CNS autoimmunity.

Laboratory Demand Management Strategies-An Overview.

Inappropriate laboratory test selection in the form of overutilization as well as underutilization frequently occurs despite available guidelines. There is broad approval among laboratory specialists as well as clinicians that demand management strategies are useful tools to avoid this issue. Most of these tools are based on automated algorithms or other types of machine learning. This review summarizes the available demand management strategies that may be adopted to local settings. We believe that artificial intelligence may help to further improve these available tools.

Presentation and formatting of laboratory results: a narrative review on behalf of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group "postanalytical phase" (WG-POST).

In laboratory medicine, much effort has been put into analytical quality in the past decades, making this medical profession one of the most standardized with the lowest rates of error. However, even the best analytical quality cannot compensate for errors or low quality in the pre or postanalytical phase of the total testing process. Guidelines for data reporting focus solely on defined data elements, which have to be provided alongside the analytical test results. No guidelines on how to format laboratory reports exist. The habit of reporting as much diagnostic data as possible, including supplemental information, may lead to an information overload. Considering the multiple tasks physicians have to do simultaneously, unfiltered data presentation may contribute to patient risk, as important information may be overlooked, or juxtaposition errors may occur. As laboratories should aim to answer clinical questions, rather than providing sole analytical results, optimizing formatting options may help improve the effectiveness and efficiency of medical decision-making. In this narrative review, we focus on the underappreciated topic of laboratory result reporting. We present published literature, focusing on the impact of laboratory result report formatting on medical decisions as well as approaches, potential benefits, and limitations for alternative report formats. We discuss influencing variables such as, for example, the type of patient (e.g. acute versus chronic), the medical specialty of the recipient of the report, the display of reference intervals, the medium or platform on which the laboratory report is presented (printed paper, within electronic health record systems, on handheld devices, etc.), the context in which the report is viewed in, and difficulties in formatting single versus cumulative reports. Evidence on this topic, especially experimental studies, is scarce. When considering the medical impact, it is of utmost importance that laboratories focus not only on the analytical aspects but on the total testing process. The achievement of high analytical quality may be of minor value if essential results get lost in overload or scattering of information by using a non-formatted tabular design. More experimental studies to define guidelines and to standardize effective and efficient reporting are most definitely needed.

Long-term peripheral immune cell profiling reveals further targets of oral cladribine in MS.

OBJECTIVES: To expand the knowledge about the immunological consequences of cladribine (CLAD), a pulsed immune reconstitution therapy approved for active multiple sclerosis (MS), beyond the known short-term effects on peripheral immune cell subsets. METHODS: In this study, we characterized depletion and restitution kinetics as well as cytokine profiles of peripheral immune cell subsets in 18 patients with MS following treatment with oral CLAD. The methods involved blood collection prior to CLAD and every three months over a period of 24 months, and extensive characterization of various immune cells subsets by multiparametric flow cytometry. RESULTS: We found a selectivity of CLAD towards central memory T cells and memory B cells and detected a hyper-repopulation of maturing B cells. Counts of classical (-65%) and various nonclassical TH17 cells (-84% to -87%) were markedly reduced 24 months after treatment start, and were comparable with depletion rates of class-switched memory B-cell phenotypes (-87% to -95%). The nadir of TH cells was more pronounced in the second treatment year. We observed a proportional surge of CD20 T-cell subsets and an expansion of regulatory T, B and NK cells. Natural killer T cells (NKT) were only depleted in year two and did not recover. INTERPRETATION: Peripheral immune cell profiling revealed more differentiated insights into the immunological effects of CLAD. While some immune cell subsets expanded, we also observed additive depleting effects after the second treatment course. Further studies are required to elucidate whether these changes are paramount for the consistent and prolonged disease-modifying effect of CLAD.

Influence of dabigatran on pro-inflammatory cytokines, growth factors and chemokines - Slowing the vicious circle of coagulation and inflammation.

AIMS: Blood coagulation is one of the most important host-defending mechanisms in vivo by maintaining the blood pressure after injury. However, besides maintaining homeostasis, blood coagulation and the contributing factors are directly linked to pathological conditions, such as thromboembolism and inflammation, leading to cardiovascular diseases, among others. As anti-inflammatory drugs may reduce cardiovascular events, we hypothesized in this study that the direct thrombin inhibitor dabigatran may reduce cytokine, growth factor and chemokine expression in vitro. MAIN METHODS: Initially, human whole blood was incubated in tubes for serum, EDTA plasma, and heparinized plasma. Furthermore, human PBMCs were isolated and incubated under different culture conditions, including the treatment with human serum or thrombin, respectively. The effect of the oral anticoagulant dabigatran on pro-inflammatory cytokines, growth factors and chemokines was investigated by ELISA. KEY FINDINGS: Conditioned serum resulted in a significant alteration of the secretome's protein levels after 24 h. However, solely ANG showed a dose-dependent increment by the addition of serum (79.8 ± 9.2 ng/mL) in comparison to baseline (0.2 ± 0.2 ng/mL), as it was in trend for thrombin treatment. Furthermore, the pre-treatment of PBMCs with different doses of dabigatran significantly lowered supernatant protein levels measured. Moreover, dabigatran was shown to decrease most notably the growth factor and chemokine levels in the PBMC's secretome that were treated with 200 ng/mL thrombin in a dose-dependent manner. SIGNIFICANCE: In conclusion, novel oral anticoagulants, such as dabigatran, could help to reduce not only procoagulatory effects in inflammatory conditions but could also reduce proinflammatory stimuli via reduced expression of cytokines and chemokines.

Errors within the total laboratory testing process, from test selection to medical decision-making - A review of causes, consequences, surveillance and solutions.

Laboratory analyses are crucial for diagnosis, follow-up and treatment decisions. Since mistakes in every step of the total testing process may potentially affect patient safety, a broad knowledge and systematic assessment of laboratory errors is essential for future improvement. In this review, we aim to discuss the types and frequencies of potential errors in the total testing process, quality management options, as well as tentative solutions for improvement. Unlike most currently available reviews on this topic, we also include errors in test-selection, reporting and interpretation/action of test results. We believe that laboratory specialists will need to refocus on many process steps belonging to the extra-analytical phases, intensifying collaborations with clinicians and supporting test selection and interpretation. This would hopefully lead to substantial improvements in these activities, but may also bring more value to the role of laboratory specialists within the health care setting.

Reducing the probability of falsely elevated HbA1c results in diabetic patients by applying automated and educative HbA1c re-testing intervals.

INTRODUCTION: Too frequent HbA1c measurements may lead to unnecessary treatment modifications of diabetic patients. The aim of this study was to estimate the percentage of falsely elevated HbA1c results in two hospitals, Landeskrankenhaus/Uniklinikum Salzburg (LKH) and Landesklinik St. Veit (STV), as well as to retrospectively investigate the effect of an automated and an educative 60-day re-testing interval (RTI). METHODS: The amount of estimated falsely elevated results (eFER), based on odds calculated using the baseline and the follow-up values and the time between these measurements, the number of HbA1c re-testings within 60 days as well as the overall number of ordered and performed HbA1c analyses were calculated. In LKH, an automated algorithm cancelling inappropriate HbA1c testing was applied, and in STV, educational actions were taken. RESULTS: Before RTI-implementation, eFER were 0.9% and 2.1% and within-60-days-re-testing were 15.0% and 7.4% of cases in LKH and STV, respectively. After RTI-implementation, these numbers decreased to 0.2% (p < .001) and 1.8% (p = .869) and within-60-days-re-testing decreased to 1.1% (p < .001) and 3.6% (p = .003) in LKH and STV, respectively. Median monthly HbA1c measurements decreased by 15.8% (p < .001) and 21.1% (p = .002) in LKH and STV, respectively. CONCLUSION: Both the educational and the automated 60-day-RTI were proven to be efficient in reducing overall HbA1c measurements, re-testing within 60 days and eFER.

The clinically effective use of cardiac markers by restructuring laboratory profiles at Cardiology wards.

Background: Laboratory overutilization is associated with diagnostic error and potential patient risk. We applied a demand management strategy in collaboration with the local Department of Cardiology to reduce the cardiac markers high-sensitive troponin T (hsTropT) and N-terminal pro brain natriuretic peptide (NTproBNP) in laboratory ordering profiles (LOPs). The present study aimed to retrospectively evaluate the implemented strategies. Methods: Strategies included educational measures and evidence-guided, active test de-selection from all cardiology ward LOPs, and/or permanent removal from LOPs. Tests remained available at all times. We evaluated overutilization by reductions in monthly orders, and assessed differences in 30-day all-cause readmission rate and length of patients' hospital stay. Results: Overall, we observed a mean reduction of 66.1% ± 7.6% (n = 277 ± 31) in hsTropT tests. Educational measures effectively reduced NTproBNP orders by 52.8% ± 17.7% (n = 60 ± 20). Permanent removal of tests from LOPs additionally decreased orders to a final extent of 75.8% ± 8.0% (n = 322 ± 31) in NTproBNP tests. The 30-day readmission rate and overall length of hospital stay did not increase. Conclusions: Our results indicate that cardiac markers in routine care are subject to extensive overutilization when used within LOPs. Educational measures are an effective strategy to overcome the overutilization of cardiac markers but may be more effective when combined with the removal of cardiac markers from LOPs.

Chemokine CXCL13 in serum, CSF and blood-CSF barrier function: evidence of compartment restriction.

BACKGROUND AND PURPOSE: Elevation of the chemokine CXCL13 in CSF frequently occurs during active and acute CNS inflammatory processes and presumably is associated with B cell-related immune activation. Elevation levels, however, vary a lot and "leaking" of CXCL13 from blood across dysfunctional brain barriers is a possible source. The aim was to clarify the relation between CXCL13 concentrations in CSF, CXCL13 concentrations in serum and blood-CSF barrier (BCSFB) function for a correct interpretation of the intrathecal origin of CXCL13. METHODS: We retrospectively analyzed CXCL13 of banked CSF/serum samples (n = 69) selected from patient records and categorized the CSF CXCL13 elevations as CXCL13 negative (< 30 pg/ml), low (30-100 pg/ml), medium (101-250 pg/ml), or high (> 250 pg/ml). CXCL13 concentrations in CSF and serum and the corresponding CSF/serum CXCL13 quotients (Qcxcl13) were compared to CSF/serum albumin quotients (QAlb) as a measure for BCSFB function. The CXCL13 negative category included two subgroups with normal and dysfunctional BCSFB. RESULTS: Serum CXCL13 concentrations were similar across categories with median levels around 100 pg/ml but differed between individuals (29 to > 505 pg/ml). Despite clear evidence in serum, CXCL13 was detectable only at trace amounts (medians 3.5 and 7.5 pg/ml) in CSF of the two CXCL13 negative subgroups irrespective of a normal or pathological QAlb. Moreover, we found no association between CSF and serum CXCL13 levels or between QAlb and CSF CXCL13 levels in any of the CSF CXCL13-delineated categories. CXCL13 apparently does not "leak" from blood into CSF. This implies an intrathecal origin also for low CSF CXCL13 levels and a caveat for analyzing the Qcxcl13, because higher serum than CSF concentrations arithmetically depress the Qcxcl13 resulting in misleadingly low CSF/serum quotients. CONCLUSION: We demonstrated that CXCL13 does not cross from blood into CSF, not even during severe BCSFB dysfunction. CSF CXCL13 elevations therefore most likely always are CNS-derived, which highlights their relevance as indicator of inflammatory CNS processes. We recommend data should not be corrected for BCSFB permeability (QAlb) and not to calculate CSF/serum quotients for CXCL13 as these may introduce error.

Inappropriate use of laboratory tests: How availability triggers demand - Examples across Europe.

INTRODUCTION: The appropriate use of laboratory diagnostics is increasingly at stake. The aim of this study was to depict some paradigmatic examples of under- and overutilization, as well as possible solutions across Europe. METHODS: We collected six examples from five European countries where a rise or decline of orders for specific laboratory parameters was observed after organizational changes but without evidence of changes in patient collective characteristics as source of this variation. RESULTS: The collected examples were the following: 1-Germany) Switch from a Brain-Natriuretic-Peptide assay to NT-pro Brain-Natriuretic-Peptide assay, resulting in a 374% increase in these analytics; 2-Spain) Implementation of a gatekeeping strategy in tumor marker diagnostics, resulting in a 15-61% reduction of these diagnostics; 3-Croatia) Stepwise elimination of creatine-kinase-MB assay from the laboratory portfolio; 4-UK) Removal of γ-glutamyl transferase from a "liver function" profile, resulting in 82% reduction of orders; 5-Austria) Implementation of a new device for rapid Influenza-RNA detection, resulting in a 450% increase of Influenza testing; 6-Spain) Insourcing of 1,25-(OH)2-Vitamin D measurements, leading to a 378% increase of these analyses. CONCLUSION: The six paradigmatic examples described in this manuscript show that availability of laboratory resources may considerably catalyze the demand, thus underscoring that inappropriate use of laboratory resources may be commonplace in routine laboratories all across Europe and most probably beyond. They also demonstrate that the application of simple strategies may assist in overcoming this issue. We believe that laboratory specialists need to refocus on the extra-analytical parts of the testing process and engage more in interdisciplinary patient-care.