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Background: Interferences on chemistry and immunoassay results due to paraproteinemia may lead to erroneous diagnoses and treatment. Such interferences are difficult to recognize and even more difficult to deal with. This report describes 1 such case where multiple measurands were affected and how the interferant was overcome., Case Report: Paraproteins present in an immunoglobulin (Ig)G-lambda multiple myeloma specimen interfered with results of total bilirubin, direct bilirubin, inorganic phosphate, iron, ferritin, and total thyroxine measured on 3 platforms: AU5800, Alinity ci, and cobas pure. Repeat testing upon dilution with normal saline or deproteinization by polyethylene glycol precipitation gave unsatisfactory results on some or all the affected measurands. Repeat testing after dilution of the interferant serum with a healthy serum corrected the anomalous results for all the affected measurands., Conclusion: Dilution of paraproteinemic serum with a healthy serum of known concentrations appears to be the most suitable method to negate the effects of paraproteinemic interferences., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society for Clinical Pathology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: The incidence of monoclonal gammopathy of undetermined significance (MGUS) in the population of over 50-year-olds is approximately 3% and increases with age. The association between MG and neuropathy has been of interest for several years, but the causal relationship has not yet been clarified., Methods: For 682 patients who visited the Department of Neurology and requested tests for MG work-up, we retrospectively collected demographic and clinical information, such as age, gender, diagnosis, and neurologic and laboratory test results, from their medical records., Results: Out of a total of 682 patients who were suspected of neuropathy and tested for monoclonal gammopathy (MG), twelve (1.76%) showed MG on their serum protein electrophoresis. The most common form was IgM-κ with five patients, followed by IgG-κ, IgG-λ, and biclonal IgG-λ and IgA-κ. The results of the immunoglobulin quantitation test and free light chain assay showed that involved M-protein values in these patients were increased. Some patients were positive for anti-myelin-associated glycoprotein (MAG) antibody, anti-GD1b IgM antibody, anti-GM1 IgG & IgM antibody, and anti-cardiolipin IgM antibody. Also, some had antinuclear antibody (ANA) or antineutrophil cytoplasmic antibody (ANCA)., Conclusions: In the future, it is necessary to investigate the pathogenic relationship between M-protein and autoantibodies in patients with neuropathies.

Background: To introduce the serum total kappa/lambda ratio (K/L) in humoral immunity testing reports to improve the detection rate of M-proteinemia., Methods: 156 M protein-positive and 5464 M protein-negative samples confirmed by serum immunofixation electrophoresis(sIFE) were accumulated from January 2021 to December 2023 in the First Affiliated Hospital of Soochow University and the contents of immunoglobulins (IgG, IgA, IgM, kappa and lambda) were tested by Beckman IMMAGE800. All the samples were divided into two groups by time: the modeling group and the validation group. The K/L values in the modeling group were analyzed by SPSS 27.0 to get the receiver operating characteristic curve (ROC). Furthermore, a more in-depth analysis was conducted to verify the reliability of the optimal cutoff values in the validation group. In addition, the levels of immunoglobulins of another group including 106 patients with definite diagnosis of monoclonal gammopathy ranging from January 2021 to June 2024 were traced back to improve the diagnostic efficiency., Results: The optimal cutoff values of K/L were 2.31 and 1.43 corresponding to K-type and L-type M-proteinemia respectively by ROC analysis. The sensitivity and specificity were validated as 76.14% and 77.42%. False positives were mainly found in samples with systemic sclerosis (36.84%), hypohepatia (28.71%) and sicca syndrome (27.27%). While false negatives were mainly found in IgA monoclonal gammopathy (38.39%) and IgM monoclonal gammopathy (28.57%). Combining with the detection rules of IgG, IgA and IgM, the sensitivities for the diagnosis of immunoglobulin light chain amyloidosis(AL) and monoclonal gammopathy of undetermined significance(MGUS) can be increased to 83.33% and 85%., Conclusions: K/L > 2.31 and K/L < 1.43 can be used as warning values for M-proteinemia. In addition, the content of the heavy chain in IgA- or IgM-type M-proteinemia may be considered to improve the detection rate., (© 2024. The Author(s).)

The clinical significance of an abnormal free light chain (FLC) test, performed due to unspecific complains in the absence of a known plasma cell dyscrasia (PCD) or lymphoproliferative disease (LPD), is not fully elucidated. We investigated the importance of an abnormal FLC ratio (FLC-R) in this setting. Patients registered in the Maccabi Healthcare Services database, tested for FLC during 2007-2023 without previously documented PCD/LPD or increased total protein (TP) level, were reviewed. Demographics, co-morbidities, and laboratory tests were recorded. FLC-R was defined as normal (0.26-1.65) or slightly (slAb 0.1-0.26/1.65-4), moderately (mAbn 0.1-0.05/4-8) and significantly abnormal (sigAb- < 0.05 or > 8). Factors associated with PCD/LPD and overall survival were identified. In total, 8,661 patients, 2,215 (25.6%) with abnormal FLC-R [2,090 (24.1%)-slAb, 65 (0.75%)-mAbn and 60 (0.7%)-sigAb], were analyzed. Almost none had anemia nor acute renal failure. 14% had concomitant increased immunoglobulins. Within a median follow-up of 52 months, 943 were diagnosed with PCD (816-MGUS, 127-MM/Amyloidosis/plasmacytoma) and 48 with LPD. Median time to PCD and LPD were 19 and 28 months. Multivariate analysis found slAb (HR = 1.8, CI95%:1.53-2.12, p < 0.001), mAbn (HR = 6.3, CI95%:4.16-9.53, p < 0.001), and sigAb FLC (HR = 10.4, CI95%:7.0-15.35, p < 0.001), to be associated with PCD/LPD diagnosis. Decreased IgG, increased IgA, and concomitant comorbidities predicted PCD, whereas increased IgM predicted LPD. Older age, male gender, anemia, decreased albumin, increased IgG and concomitant comorbidities, predicted shorter survival. Our large study emphasizes the independent clinical significance of abnormal FLC-R as a predictor of PCD/LPD diagnosis even in patients with normal TP level, promoting early detection of PCD/LPD., (© 2024. The Author(s).)

The diagnosis of multiple myeloma requires detection of paraproteinemia and confirmation of monoclonal bone marrow infiltration, along with signs of end-organ damage. Despite the increasing prevalence, serum paraproteinemia is not routinely measured. We examined the relationship between alterations in routine hematological parameters and the development of paraproteinemia in a case-control study. Data was retrieved from a laboratory database in the capital region of Denmark between 01/01/2012 and 31/12/2022. Patients were included if they had a test for paraproteinemia (n = 134,740) and at least one prior hematological parameter (white blood cells, hemoglobin and platelet count) with a minimum follow-up of 1 year.Between 96,999 and 103,590 patients were included in each of the three hematological groups. We found white blood cell count and the presence of paraproteinemia followed an inverse J-shaped curve, with the highest presence below 3 × 10 9 /L and above > 9 × 10 9 /L. The adjusted OR below and above the nadir of 4 × 10 9 /L was 1.61 (95% CI 1.25; 2.08, p < 0.0001) and 1.03 (95% CI 1.03; 1.04, p < 0.0001). Hemoglobin levels were inversely associated the presence of paraproteinemia, with the highest association below 6 mmol/L with an OR of 1.30 (95% CI 1.28; 1.32, p < 0.0001) adjusted for age and gender. Platelet count followed a U-shaped curve with the highest association at < 100 × 10 9 /L. The adjusted OR below and above the nadir of 250 × 10 9 /L was 1.13 (95% CI 1.10; 1.17, p < 0.0001) and 1.10 (95% CI 1.08; 1.12, p < 0.0001) respectively. In conclusion, all three parameters showed significant association with later paraproteinemia., (© 2024. The Author(s).)

Current guidelines recommend screening with serum M-protein and serum-free light chain analysis (S-FLC) when an M-protein-related disorder is suspected. Many patients with multiple myeloma will be overlooked if only serum M-protein is measured. Despite this, the general practitioners in some areas of Denmark cannot order S-FLC. This review aims to disseminate knowledge of the S-FLC analysis, its applicability, and limitations in the diagnostic workup for suspected monoclonal gammopathies., (Published under Open Access CC-BY-NC-BD 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/.)

Background: Isoelectric focusing (IEF) is a method with an exquisite resolution, and coupled with affinity immunoblotting (AIB), it can provide superior sensitivity to detect monoclonal free light chains (FLC)., Methods: We tested the hypothesis that IEF/AIB is more sensitive and specific for monoclonal FLC detection in serum and urine samples than conventional methods, that is, electrophoresis (ELP), immunofixation (IF) and serum FLC ratio assessment. Investigation included 107 samples of 68 patients, among which 21 multiple myeloma patients were recently tested for minimal residual disease and 18 patients with AL amyloidosis., Results: Monoclonal FLC were detected by IEF/AIB in 37% of serum samples negative for monoclonal FLC on ELP/IF. As for urine samples, significant advantage of the IEF/AIB over ELP/IF was not demonstrated. Considering both serum and urine results, IEF/AIB definitely revealed monoclonal FLC in 20/83 (24%) of ELP/IF-negative samples. FLC ratio was abnormally high (>1.65) in all 11 patients definitely positive for monoclonal FLC kappa by IEF/AIB but also in 16/47 (34%) IEF/AIB-negative samples. Abnormally low values (<0.26) were found only in 10/28 samples (36%) positive for monoclonal FLC lambda. Appropriate use of renal FLC ratio reference range reduced the number of presumably false positives (6/47, i.e. 13%) but not false negatives (17/28, i.e. 61%)., Conclusions: The IEF/AIB method is more sensitive than IF and might be used in patients with negative IF results before deciding whether to proceed to minimal residual disease testing., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Upon infection activated plasma cells produce large quantities of antibodies which can lead to the emergence of a monoclonal component (MC), detectable by serum protein electrophoresis (SPEP). This study aims to investigate any correlation between SARS-CoV-2 infection and MC development and, if identified, whether it persists during follow-up., Methods: SPEPs of 786 patients admitted to hospitals between March 01 2020 and March 31 2022 were evaluated. Positive (SARS-CoV-2+) and negative (SARS-CoV-2-) patients to nasopharyngeal swab for SARS-CoV-2 by RT-PCR were included. The persistence/new occurrence of MC was investigated for all patients during follow-up. Patient groups were compared by chi-square analysis., Results: MC was identified in 12% of all patients admitted to hospital, of which 28.7% were SARS-CoV-2+. The most common immunoglobulin isotype in both groups was IgG-k. There was no correlation between MC development and SARS-CoV-2 infection (p = 0.173). Furthermore, the risk of MC persistence in SARS-CoV-2-negative patients was revealed to be higher than in the SARS-CoV-2+ at follow-up (HR = 0.591, p = 0.05)., Conclusions: Our study suggests that the detection of MC during SARS-CoV-2 infection is most likely due to the hyperstimulation of the humoral immune system, as also occurs in other viral infections., (© 2024 John Wiley & Sons Ltd.)

Flow cytometry plays an important role in the diagnosis and treatment of plasma cell diseases, particularly in the detection of circulating plasma cells (CPCs) in the peripheral blood. A consensus about the normalized use of flow cytometry in detection of CPCs in peripheral blood in clinical practice has been achieved. This consensus is founded on evidence-based principles, which elucidates the timing and value of flow cytometry for the detection of CPCs in the monoclonal gammopathy of undetermined significance, smoldering myeloma, multiple myeloma, and plasma cell leukemia and standardizes flow cytometry in the detection of CPCs in plasma cell diseases.

Objectives: To verify the analytical performance of a new mass spectrometry-based method, termed MASS-FIX, when screening for plasma cell disorders in a routine clinical laboratory., Patients and Methods: Results from 19,523 unique patients tested for an M-protein between July 24, 2018, and March 6, 2020, by a combination serum protein electrophoresis (SPEP) and MASS-FIX were examined for consistency with pretest implementation performance. MASS-FIX's ability to verify abnormal results from SPEP and free light chain measurements was then compared with that of immunofixation electrophoresis (IFE) using a separate cohort of 52,586 patients tested by SPEP/IFE during the same period., Results: Overall, 62.4% of our cohort was negative for an M-protein. Importantly, 7.3% of all specimens had an M spike on SPEP (0.1 to 8.5 g/dL) and MASS-FIX detected an M-protein in all these samples. Of all samples, 30.3% had M-proteins that were detected by MASS-FIX but the SPEP finding was too small for quantification. Of the positive samples, 5.7% contained a therapeutic monoclonal antibody. Of the positive samples, 4.1% had an N-glycosylated light chain (biomarker of high-risk plasma cell disorders). MASS-FIX confirmed a higher percentage of SPEP abnormalities than IFE. MASS-FIX was slightly more sensitive than IFE when confirming an M-protein in samples with an abnormal free light chain ratio. MASS-FIX had a very low sample repeat rate (1.5%). MASS-FIX was highly automatable resulting in a higher number of samples/technologist/day than IFE (∼30% more)., Conclusion: Overall, MASS-FIX was successful in maintaining validation characteristics. MASS-FIX was more sensitive in confirming SPEP abnormalities when compared with IFE. Ability to detect therapeutic monoclonal antibodies and glycosylated light chains was distinctly advantageous., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Multiple myeloma (MM) remains an incurable plasma cell malignancy. While its origin is enigmatic, an association with infectious pathogens including hepatitis C virus (HCV) has been suggested. Here we report nine patients with monoclonal gammopathy of undetermined significance (MGUS) or MM with previous HCV infection, six of whom received antiviral treatment. We studied the evolution of the gammopathy disease, according to anti-HCV treatment and antigen specificity of purified monoclonal immunoglobulin, determined using the INNO-LIA™ HCV Score assay, dot-blot assays, and a multiplex infectious antigen microarray. The monoclonal immunoglobulin from 6/9 patients reacted against HCV. Four of these patients received antiviral treatment and had a better evolution than untreated patients. Following antiviral treatment, one patient with MM in third relapse achieved complete remission with minimal residual disease negativity. For two patients who did not receive antiviral treatment, disease progressed. For the two patients whose monoclonal immunoglobulin did not react against HCV, antiviral treatment was not effective for MGUS or MM disease. Our results suggest a causal relationship between HCV infection and MGUS and MM progression. When HCV was eliminated, chronic antigen-stimulation disappeared, allowing control of clonal plasma cells. This opens new possibilities of treatment for MGUS and myeloma., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Rodríguez-García, Linares, Morales, Allain-Maillet, Mennesson, Sanchez, Alonso, Leivas, Pérez-Rivilla, Bigot-Corbel, Hermouet and Martínez-López.)

Objective: To investigate the demographic and clinicopathological features and renal outcomes of Chinese patients with C3 glomerulonephritis in the setting of monoclonal gammopathy., Methods: Patients with renal biopsy-proven C3 glomerulonephritis and detectable serum and/or urine monoclonal immunoglobulin from 2006 to 2018 in Peking University First Hospital were included, their clinical data, renal pathology type, treatment, and prognosis were collected and analyzed., Results: Nineteen patients were enrolled, accounting for 24% of C3GN patients in the study period. The mean age of onset was 55 years old and the gender ratio was 4/15 (female/male). The mean eGFR at biopsy was 49.55 ± 29.81 ml/min/1.73m 2 . The prominent clinical manifestations included nephrotic syndrome (58%), anemia (68%), microscopic hematuria and leukocyturia (58%), and hypocomplementemia (13, 68%). The IgG was the most common isotype of monoclonal Ig on immunofixation electrophoresis. Kidney biopsies revealed a relatively prominent MPGN pattern. Only two patients had direct evidence of monocle immunoglobulins acting as C3GN pathogenic factors. Two patients had concurrent TMA-like renal injuries. The median renal survival was 12 and 15 months, respectively in patients receiving conservative therapy and immunosuppressant therapy, without statistical significance. The efficacy of clone-targeted therapy needed further investigation. Plasma exchange therapy only improved one patient's renal outcome., Conclusions: This is the first case series report of C3GN combined with monoclonal Ig in northern China. The renal prognosis of these patients is poor, and immunosuppressant therapies show no advantage over supportive therapy in renal prognosis, while the benefit of clone-targeted chemotherapy is still requiring investigation.

The detection and quantification of immunoglobulin free light chains in serum and urine is recommended for the diagnosis and monitoring of monoclonal gammopathies according to the guidelines of the International Myeloma Working Group (IMWG). Several tests are currently available in the clinical laboratory to detect and quantify free light chains but although quality, efficiency, and effectiveness have been improved, the results are still variable and poorly harmonized and standardized. The present review article wants to analyze these aspects, with a keen eye on techniques, such as mass spectrometry, that could replace in the practical clinical laboratory the current methods including Bence-Jones protein assay and free light chain immunoassays., (Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Mass spectrometry has recently been proposed as a novel sensitive screening tool for monoclonal gammopathies. In a small study we have tested the ability of quantitative immunoprecipitation mass spectrometry (QIP-MS) to identify low level monoclonal immunoglobulins not currently detected by the initial serum protein electrophoresis (SPEP) screen. QIP-MS positively identified the primary monoclonal immunoglobulins in all 11 patient samples alongside additional monoclonal immunoglobulins in a subset of patient samples. We conclude that QIP-MS has clinical utility as a first-line screening tool for monoclonal gammopathy investigation, identifying monoclonality in patients with higher sensitivity and resolution compared to the current standard methods., (Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Introduction: AL amyloidosis (AL) is a malignant form of plasma cell dyscrasia (PCD). It is insidious, and its end-organ damage can mimic that of common diseases. At diagnosis, routine tests for monoclonal protein are insufficient for the differential diagnosis. We hypothesized that Hevylite ® (HLC) isotype patterns may help discriminate between AL and benign PCD states., Methods: Serum samples of patients with a high clinical suspicion of AL were prospectively tested for IgGκ, IgGλ, IgAκ, IgAλ, IgMκ, and IgMλ concentrations and ratios using Hevylite ® assays in a blinded manner. The results were correlated with the final diagnosis., Results: Of the 99 samples analyzed, 46 were newly diagnosed AL, and the majority, 38 (82.6%), presented with suppression of at least one HLC isotype. Of the 53 benign PCD patients, 36 (67.9%) presented with elevation of at least one HLC isotype. By multivariate analysis, Hevylite ® was the best independent test predictor of AL amyloidosis. HLC suppression had an odds ratio (OR) of 14.591, and elevation an OR of 10.149, and thus were significant variables in the diagnosis and exclusion of AL. Furthermore, patients with both HLC suppression, together with no elevation, had an OR of 316.69 to be diagnosed with AL rather than a benign PCD., Conclusions: Hevylite ® HLC analysis for Ig isotypes patterns offers an effective non-invasive tool in the evaluation of patients with high suspicion of AL and may assist further explorative decisions for diagnosis., (© 2021 John Wiley & Sons Ltd.)

Objective: Monoclonal protein (MP) exists in various diseases, and capillary electrophoresis (CE) has been widely used to detect MP. However, there is not much research on the application value of MP in the differential diagnosis of monoclonal gammopathies. This study aimed to explore MP's cutoff value for the differential diagnosis of multiple myeloma (MM) and other monoclonal gammopathies (MGs)., Methods: A retrospective analysis of 8167 cases was conducted. Serum MP was detected by CE, and the patients' clinical information was collected from the clinical database of our hospital., Results: 985 cases had MP with high peaks, and 91.1% were diagnosed with malignant diseases. The MP showed small peaks in 471 cases, and only 24.4% were diagnosed with malignant diseases. Among the MPs, the IgG-κ type was the most common type, followed by the IgG-λ, IgA-κ, IgA-λ, free λ light chain, IgM-κ, free κ light chain, double clone, and IgM-λ types. Differences in the MP of the IgG, IgA, IgM, and FLC types between the MM group and MGUS group were statistically different ( P <0.01). The MP of the IgG, IgA, and FLC types showed clear specificity and sensitivity in discriminating MM from other monoclonal gammopathies in ROC curve analysis. Serum IgM had statistical significance in the differential diagnosis between WM and other MGs ( P <0.01). However, there was no statistical significance in the differential diagnosis between MM and other MGs ( P =0.140). The cutoff values of the MP of the IgG, IgA, and FLC types were >18.67g/L, >13.86g/L, and >10.15g/L, respectively, for the differential diagnosis of MM and other MGs. The cutoff value of the MP of IgM for the WM diagnosis was >37.75 g/L., Conclusion: CE has good clinical application value in the diagnosis of monoclonal gammopathies, and MP can be used in the differential diagnosis of MM and other monoclonal gammopathies., (© 2021 by the Association of Clinical Scientists, Inc.)

Measurable residual disease (MRD) assessment by marrow-based next-generation flow cytometry (NGF) following autologous stem cell transplantation (ASCT) may lead to false-negative results due to patchy marrow involvement and extramedullary disease in patients with multiple myeloma. We assessed the value of simultaneous MRD evaluation with NGF and serum matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MASS-FIX). Of all 61 complete responders who were NGF-negative for MRD, around day-100 post ASCT, 59% were MASS-FIX-positive. At median follow-up of 26 months, 69% of MASS-FIX(+)/NGF(-) patients were alive and progression-free versus 96% of MASS-FIX(-)/NGF(-) patients, P = 0·02. MASS-FIX, a simple peripheral blood-based assay complements marrow-based NGF to accurately prognosticate patients with myeloma., (© 2020 British Society for Haematology and John Wiley & Sons Ltd.)

Immunoenrichment-based matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), termed MASS-FIX, offers several advantages over immunofixation for the detection and isotyping of serum monoclonal protein, including superior sensitivity and specificity, the ability to differentiate therapeutic monoclonal antibodies, and the rapid identification of light chain (LC) N-glycosylation. We identified 6315 patients with MASS-FIX performed at our institution since 2018. Of these, 4118 patients (65%) with a wide array of plasma cell disorders (PCD), including rare monoclonal gammopathies of clinical significance, had a positive MASS-FIX. Two-hundred twenty-one (5%) of the MASS-FIX positive patients had evidence of LC N-glycosylation, which was more commonly identified in IgM heavy chain isotype, kappa LC isotype, and in diagnoses of immunoglobulin light chain (AL) amyloidosis and cold agglutinin disease (CAD) compared to other PCD. This cross-sectional study describes the largest cohort of patients to undergo MASS-FIX in routine clinical practice. Our findings demonstrate the widespread utility of this assay, and confirm that LC N-glycosylation should prompt suspicion for AL amyloidosis and CAD in the appropriate clinical context.

Several studies in chronic lymphocytic leukemia (CLL) patients have reported impaired immune cell functions, which contribute to tumor evasion and disease progression. However, studies on CLL-like monoclonal B-cell lymphocytosis (MBL) are scarce. In the study described here, we characterized the immune environment in 62 individuals with clinical MBL, 56 patients with early-stage CLL, and 31 healthy controls. Gene expression arrays and quantitative reverse transcription polymerase chain reaction were performed on RNA from CD4 + peripheral blood cells; serum cytokines were measured with immunoassays; and HLA-DR expression on circulating monocytes, as well as the percentages of Th1, cytotoxic, exhausted, and effector CD4 + T cells, were evaluated by flow cytometry. In addition, cell cultures of clonal B cells and CD14-enriched or -depleted cell fractions were performed. Strikingly, MBL and early-stage CLL differed in pro-inflammatory signatures. An increased inflammatory drive orchestrated mainly by monocytes was identified in MBL, which exhibited enhanced phagocytosis, pattern recognition receptors, interleukin-8 (IL8), HMGB1, and acute response signaling pathways and increased pro-inflammatory cytokines (in particular IL8, interferon γ [IFNγ], and tumor necrosis factor α). This inflammatory signature was diminished in early-stage CLL (reduced IL8 and IFNγ levels, IL8 signaling pathway, and monocytic HLA-DR expression compared with MBL), especially in those patients with mutations in IGHV genes. Additionally, CD4 + T cells of MBL and early-stage CLL exhibited a similar upregulation of Th1 and cytotoxic genes and expanded CXCR3 + and perforin + CD4 + T cells, as well as PD1 + CD4 + T cells, compared with controls. Cell culture assays disclosed tumor-supporting effects of monocytes similarly observed in MBL and early-stage CLL. These novel findings reveal differences in the inflammatory environment between MBL and CLL, highlighting an active role for antigen stimulation in the very early stages of the disease, potentially related to malignant B-cell transformation., Competing Interests: Conflict of interest disclosure The authors have no financial conflicts of interest., (Copyright © 2021 ISEH -- Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

Factor H (FH), a member of the regulators-of-complement-activation (RCA) family of proteins, circulates in human plasma at concentrations of 180-420 mg/L where it controls the alternative pathway (AP) of complement in the fluid phase and on cell surfaces. When the regulatory function of FH is impaired, complement-mediated tissue injury and inflammation occur, leading to diseases such as atypical hemolytic uremic syndrome (a thrombotic microangiopathy or TMA), C3 glomerulopathy (C3G) and monoclonal gammopathy of renal significance (MGRS). A pathophysiological cause of compromised FH function is the development of autoantibodies to various domains of the FH protein. FH autoantibodies (FHAAs) are identified in 10.9% of patients with aHUS, 3.2% of patients with C3G, and rarely in patients with MGRS. The phenotypic variability of FHAA-mediated disease reflects both the complexity of FH and the epitope specificity of FHAA for select regions of the native protein. In this paper, we have characterized FHAA epitopes in a large cohort of patients diagnosed with TMA, C3G or MGRS. We explore the epitopes recognized by FHAAs in these diseases and the association of FHAAs with the genetic deletion of both copies of the CFHR1 gene to show how these disease phenotypes are associated with this diverse spectrum of autoantibodies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Zhang, Ghiringhelli Borsa, Shao, Dopler, Jones, Meyer, Pitcher, Taylor, Nester, Schmidt and Smith.)

CANOMAD (chronic ataxic neuropathy, ophthalmoplegia, immunoglobulin M [IgM] paraprotein, cold agglutinins, and disialosyl antibodies) is a rare syndrome characterized by chronic neuropathy with sensory ataxia, ocular, and/or bulbar motor weakness in the presence of a monoclonal IgM reacting against gangliosides containing disialosyl epitopes. Data regarding associated hematologic malignancies and effective therapies in CANOMAD are scarce. We conducted a French multicenter retrospective study that included 45 patients with serum IgM antibodies reacting against disialosyl epitopes in the context of evocating neurologic symptoms. The main clinical features were sensitive symptoms (ataxia, paresthesia, hypoesthesia; n = 45, 100%), motor weakness (n = 18, 40%), ophthalmoplegia (n = 20, 45%), and bulbar symptoms (n = 6, 13%). Forty-five percent of the cohort had moderate to severe disability (modified Rankin score, 3-5). Cold agglutinins were identified in 15 (34%) patients. Electrophysiologic studies showed a demyelinating or axonal pattern in, respectively, 60% and 27% of cases. All patients had serum monoclonal IgM gammopathy (median, 2.6 g/L; range, 0.1-40 g/L). Overt hematologic malignancies were diagnosed in 16 patients (36%), with the most frequent being Waldenström macroglobulinemia (n = 9, 20%). Forty-one patients (91%) required treatment of CANOMAD. Intravenous immunoglobulins (IVIg) and rituximab-based regimens were the most effective therapies with, respectively, 53% and 52% of partial or better clinical responses. Corticosteroids and immunosuppressive drugs were largely ineffective. Although more studies are warranted to better define the optimal therapeutic sequence, IVIg should be proposed as the standard of care for first-line treatment and rituximab-based regimens for second-line treatment. These compiled data argue for CANOMAD to be included in neurologic monoclonal gammopathy of clinical significance., (© 2020 by The American Society of Hematology.)

Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a condition characterized by a hyperinflammatory state and persistent macrophage activation, resulting in reactive phagocytosis of the hematopoietic elements. In children, it is usually a hereditary disorder, while in adults it is usually acquired secondary to viral infections, collagenoses, or tumors. Although accounting for 10% of hematologic malignancies, HLH is rarely associated with multiple myeloma (MM) and other plasmacytic dyscrasias., Patient Concerns: A 64-year-old Brazilian man seeked medical care with a 3-month history of intermittent fever, weight loss, night sweats, and progressive anemic symptoms., Diagnosis: Total blood count showed severe bicytopenia (normocytic-normochromic anemia and thrombocytopenia), biochemical exams showed elevation of creatinine, as well as monoclonal peak in serum protein electrophoresis, high IgA dosage, and serum immunofixation with IgA kappa paraprotein. Bone marrow biopsy showed 30% of monoclonal and phenotypically anomalous plasmocytes, confirming the diagnosis of MM. Diagnosis of HLH was established by the presence of clinical and laboratory criteria: fever, splenomegaly, cytopenias, hypofibrinogenemia, hyperferritinemia, elevation of triglycerides, and several figures of erythrophagocytosis in bone marrow aspirate., Interventions: The patient experienced pulse therapy with methylprednisolone for hemophagocytic lymphohistiocytosis, followed by initial therapy for multiple myeloma with cyclophosphamide and dexamethasone., Outcomes: Once the diagnosis of MM and secondary hemophagocytic syndrome was established, the patient had a rapid clinical deterioration despite the established therapeutic measures, evolving with cardiovascular failure, acute liver failure, acute disseminated intravascular coagulation, worsening renal dysfunction requiring dialysis support, respiratory dysfunction, and lowering of consciousness, characterizing rapid multiple organ dysfunction, ultimately leading to the death of the patient., Innovation: Here, we aimed to describe the sixth reported case of HLH associated with MM, according to cases cataloged in the PubMed database, and the first case evaluated by 18-fluordeoxyglucose positron emission tomography (18-FDG-PETCT)., Conclusion: Our case report seeks to provide support for a better clinical and laboratory characterization of this rare paraneoplastic entity associated with MM, and aims to call the attention of hematologists and intensivists to this condition that falls within the scope of the differential diagnosis of rapid onset multiple organ failure in patients with plasmacytic neoplasms.

Medical technologists who perform serum protein electrophoresis can provide valuable input and assistance in the interpretation of the electrophoretic pattern. Recognition of common alterations in conjunction with the utilization of standardized interpretation comments expedites the final interpretation performed by the clinical pathologist. Improved understanding of the clinical utility of the electrophoretic interpretation enhances the role and satisfaction of the medical technologists., (© 2020 by the Association of Clinical Scientists, Inc.)

The relationship between chronic lymphocytic leukaemia (CLL) and qualitative/quantitative gammaglobulin abnormalities is well established. Nevertheless, in order to better understand this kind of connection, we examined 1505 patients with CLL and divided them into four subgroups on the basis of immunoglobulin (Ig) aberrations at diagnosis. A total of 73 (4·8%), 149 (10%), 200 (13·2%) and 1083 (72%) patients were identified with IgM monoclonal gammopathy (IgM/CLL), IgG monoclonal gammopathy (IgG/CLL), hypogammaglobulinaemia (hypo-γ) and normal Ig levels (γ-normal) respectively. IgM paraprotein was significantly associated with a more advanced Binet/Rai stage and del(17p)/TP53 mutation, while IgG abnormalities correlated with a higher occurrence of trisomy 12. Patients with any type of Ig abnormality had shorter treatment-free survival (TFS) but no significant impact affecting overall survival (OS) compared to those with normal Ig levels., (© 2020 British Society for Haematology and John Wiley & Sons Ltd.)

Background: Crystalglobulin-associated nephropathy (CAN), a rare subtype of monoclonal gammopathy, usually associated with multiple myeloma and occasionally monoclonal gammopathy of uncertain significance (MGUS), is characterized by occluding monoclonal pseudothrombi within renal glomerular capillaries and/or interstitial arterioles. Ultrastructurally, these pseudothrombi are unique for having a crystalline substructure. We describe a case of an adult patient with monoclonal B-cell lymphocytosis (MBL) and acute renal failure whose kidney biopsy revealed a rare diagnosis of CAN., Case Presentation: A 63-year old male presented with a 2-month history of edema, arthralgia and malaise. He had acute kidney injury with hematoproteinuria on urine analysis. Serum and urine protein electrophoresis were both negative. A renal biopsy however revealed features of CAN. Organomegaly, bone pain and lymphadenopathy were absent. A repeat serum electrophoresis was positive for IgA kappa and a free light chain assay showed elevated free kappa light chains. Flow cytometry done subsequently revealed a diagnosis of MBL, chronic lymphocytic leukemia (CLL) type., Conclusion: CAN in association with MBL/CLL has not been previously described in literature, and our case highlights yet another instance of monoclonal gammopathy of renal significance (MGRS) where a small B-cell clone resulted in extensive renal pathology without systemic manifestations.

A 72-year-old Japanese man with diabetes mellitus and hypertension presented with an acutely elevated serum creatinine level, from 1.02 to 4.13 mg/dL over 2 months as measured by the enzymatic method by pure-auto S CRE-N ® . Renal biopsy could not identify the etiology of the elevating sCr. However, an elevated total protein level (8.2 g/dL) and lowering of the BUN and sCr ratio from 14.5 to 2.7 were found, and bone marrow biopsy showed less than 10% lymphoplasmacytic infiltration, compatible with monoclonal gammopathy of undetermined significance. The diagnosis of a false serum creatinine elevation due to monoclonal gammopathy of undetermined significance was confirmed with the serum cystatin C level at 1.05 mg/dL and the creatinine level of 0.97 mg/dL using Shikarikid-S CRE ® method. Although cases of monoclonal gammopathy of undetermined significance with a false serum creatinine elevation as an initial presentation are rare, this condition should be considered in patients with paraproteinemia; measuring the renal function using cystatin C is important in such patients.

The TEMPI syndrome is a rare and acquired disorder characterized by 5 salient features, which compose its name: (1) telangiectasias; (2) elevated erythropoietin and erythrocytosis; (3) monoclonal gammopathy; (4) perinephric fluid collections; and (5) intrapulmonary shunting. Complete resolution of symptoms following treatment with plasma cell-directed therapy supports the hypothesis that the monoclonal antibody is causal and pathogenic. Understanding the basis of the TEMPI syndrome will depend on the identification of additional patients and a coordinated international effort., (© 2020 by The American Society of Hematology.)

Background: Plasma cell dyscrasias (PCD) are a heterogeneous group of diseases characterized by the expansion of monoclonal bone marrow plasma cells that produce a monoclonal immunoglobulin (M-component)., Purpose: This is a retrospective study that describes the epidemiological, immunochemical features and etiology of monoclonal gammopathies diagnosed between 1998 and 2016 in the Teaching Hospital Beni-Messous of Algiers., Patients and Methods: 2121 cases of monoclonal gammopathies (MG) were collected during this period. Serum/urine protein electrophoresis, serum/urine immunofixation and serum free light chain measurements were used to demonstrate M protein., Results: The middle age of the patients at the time of the diagnosis were 62.96 ± 13.19 years with extremes ranging from 07 to 99 years. The study included 1013 (47, 76 %) men and 1108 (52, 23 %) women with a sex ratio 0,91. Isotypes repartition was: IgG (60.91 %), IgA (17.91 %), light chain (10.46 %), IgM (6.6 %), IgD (1.03 %) and IgE (0.09 %) of cases. The most frequent diagnosis was: Multiple Myeloma (55.20 %), followed by monoclonal gammopathy of undetermined significance (34.13 %)., Conclusion: In our study, two particularities were noted. There is no male predominance in Algerian PCD patients. Moreover, we observed a higher frequency of light chain multiple myeloma and lower frequency of IgM isotype compared to western studies., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Serum κ and λ free light chain levels are markers of plasma cell proliferation, and their measurements have been included in recent guidelines by the International Myeloma Working Group for the management of patients with plasma cellular dyscrasias. Five in vitro diagnostic methods for the immunochemical quantification of serum free light chains (FLC) are available, three based on polyclonal antibodies (Freelite ® , The Binding Site; FLC ELISA κ and λ, Sebia; human κ and λ FLC, Diazyme Laboratories) and two on monoclonal antibodies (N Latex FLC, Siemens Healthineers; Seralite ® , Sebia). Several studies have shown that these methods cannot be used interchangeably for the follow-up of patients because measured κ and λ FLC concentrations may differ significantly, especially at high levels. Because no international reference material for the measurement of FLC is available, it is not possible to establish which method is the most accurate. For this reason, knowledge about the analytical and diagnostic performances of the assays used is important. The aim of this review is to describe the main analytical features of the κ and λ FLC assays and how they may influence the clinical use of these parameters.

Gaucher disease (GD) is a rare lysosomal autosomal-recessive disorder due to deficiency of glucocerebrosidase; polyclonal gammopathy (PG) and/or monoclonal gammopathy (MG) can occur in this disease. We aimed to describe these immunoglobulin abnormalities in a large cohort of GD patients and to study the risk factors, clinical significance, and evolution. Data for patients enrolled in the French GD Registry were studied retrospectively. The risk factors of PG and/or MG developing and their association with clinical bone events and severe thrombocytopenia, two markers of GD severity, were assessed with multivariable Cox models and the effect of GD treatment on gammaglobulin levels with linear/logarithmic mixed models. Regression of MG and the occurrence of hematological malignancies were described. The 278 patients included (132 males, 47.5%) were followed up during a mean (SD) of 19 (14) years after GD diagnosis. PG occurred in 112/235 (47.7%) patients at GD diagnosis or during follow-up and MG in 59/187 (31.6%). Multivariable analysis retained age at GD diagnosis as the only independent risk factor for MG (> 30 vs. ≤30 years, HR 4.71, 95%CI [2.40-9.27]; p < 0.001). Risk of bone events or severe thrombocytopenia was not significantly associated with PG or MG. During follow-up, non-Hodgkin lymphoma developed in five patients and multiple myeloma in one. MG was observed in almost one third of patients with GD. Immunoglobulin abnormalities were not associated with the disease severity. However, prolonged surveillance of patients with GD is needed because hematologic malignancies may occur.

IgM paraprotein-associated peripheral neuropathy (PN) in patients without overt evidence of lymphoma is a recognised clinical entity of unknown aetiology. Interrogating the bone marrow B-cell or plasma cell clones underlying paraproteinemic neuropathies may improve our understanding of both pathogenesis and treatment options. This retrospective observational analysis of IgM paraprotein-associated PN identified five patients with small pathological MYD88 L265P and CD20-positive B-cell clones in their bone marrow using multi-parametric flow cytometry, who have shown durable neurological response to rituximab. We posit that multi-parametric flow cytometry may be instrumental in identifying the cellular source of the paraprotein in IgM paraprotein-associated PN, and thus directing appropriate immunomodulatory therapy. Further understanding of these small pathological B-cell clones may also provide additional insight into mechanisms of monoclonal gammopathy of clinical significance overall., (© 2019 British Society for Haematology and John Wiley & Sons Ltd.)

Background: The analysis of serum free light chains (FLCs) is clinically relevant for the diagnosis and therapeutic management of clonal plasma cell disorders. This study compares the performance of monoclonal and polyclonal FLC κ and λ assays in clinical samples determined in a single academic center., Methods: Serum FLCs were analyzed from 102 patients using the Freelite (Binding Site) and N Latex (Siemens) assays on the BN ProSpec System (Siemens). When available, data for protein electrophoresis, immunofixation, C-reactive protein, and estimated glomerular filtration rate (eGFR) were combined with FLC results to evaluate performance., Results: Method evaluation showed acceptable imprecision and inaccuracy measures of <4.4% and 12.9%, respectively. Poor agreement between the methods was observed, including constant and proportional bias and poor correlation (Kendall τ, 0.671-0.901). The N Latex assay was not affected by the renal impairment estimated by eGFR, unlike the FLC κ/λ ratio results by the Freelite assay. With the Freelite assay, 98% of putative controls without monoclonal gammopathy (n = 42) showed a κ/λ ratio that was above the median of the standard diagnostic range or renal diagnostic range. A shift toward higher κ/λ ratios was also observed when retrospective data between 2011 and 2017 were compared., Conclusions: Unlike the Freelite assay, κ/λ ratios analyzed with the N Latex assay were not affected by renal failure. Both methods showed acceptable performances using nephelometry, but they were poorly correlated. A shift toward κ/λ ratios might impair the specificity of borderline increased κ/λ results. This should be considered when interpreting FLC κ and λ results., (© 2019 American Association for Clinical Chemistry.)

Background: Although most cases of tubulointerstitial nephritis in paraproteinemia are monoclonal light chain deposition-mediated, interstitial nephritis as neoplastic interstitial cell infiltration has rarely been described. On the other hand, lympho-plasma-cell-rich tubulointerstitial nephritis, in which the infiltrative cells are usually polytypic, is often evident in primary Sjögren's syndrome (pSS). Herein we present a rare case of pSS in a patient who had been diagnosed as having IgA kappa-type monoclonal gammopathy of undetermined significance (MGUS) and developed tubulointerstitial nephritis with monotypic (IgA kappa) lympho-plasmacytic infiltrates., Case Presentation: A 74-year-old Japanese woman with pSS who had been diagnosed as having IgA kappa-type MGUS developed progressive renal dysfunction. Renal biopsy revealed tubulointerstitial nephritis with abundant plasma cell-rich mononuclear cell infiltrates without atypia. Immunohistochemical staining for immunoglobulins and light chains showed that most infiltrates were positive for IgA and kappa. Most of the infiltrative cells were positive for CD38 and CD138, and cells positive for CD 19 and CD 45 were also widely evident. Electron microscopy and immunofluorescence studies revealed no apparent immunological deposits in the glomeruli and tubules. Bone marrow and whole-body radiological examinations revealed no findings suggestive of multiple myeloma or lymphoma. Renal function improved rapidly with prednisolone 40 mg daily and has been maintained at the same level on low-dose prednisolone and azathioprine for 18 months., Conclusion: Tubulointerstitial nephritis with monotypic cell infiltrates, without immunological deposits, is a quite rare histological picture in MGUS, and might be a unique renal manifestation in patients with pSS.

Background: C3 glomerulonephritis (C3GN) is a rare disease caused by inherited or acquired complement alternative pathway (CAP) dysregulation, which could also be secondary to monoclonal gammopathy of undetermined significance (MGUS). Herein, we described a patient presenting with C3GN and monoclonal gammopathy, and the pathogenic association between the two diseases was further explored in vitro., Case Presentation: A 76-year-old Chinese man presented with low serum C3 level, haematuria and nephrotic syndrome, and experienced rapid worsening of renal function over a period of 10 months. His serum and urine immunofixation electrophoresis both revealed a monoclonal IgGλ. A bone marrow puncture showed plasma cell dyscrasias with the highest plasma cell count of 5.25%. Kidney biopsy showed the presence of C3 glomerulonephritis, with exclusive deposits of C3 visible on immunofluorescence, a membranoproliferative pattern on light microscopy and electron dense deposits in sub-epithelial, intramembranous, sub-endothelial and mesangial regions by electron microscopy. The patient was positive for C3 nephritic factor (C3NeF) activity and anti-CFH autoantibodies, and all became negative during disease remission. The anti-CFH autoantibodies purified from the patient's plasma exchange fluids were proven to be a monoclonal IgGλ, and could inhibit CFH binding to C3b and accelerate the formation of C3 convertase indirectly by interfering with the formation-impeding activity of CFH. No deficiency of candidate genes, especially variants in CFH, was detected in our patient. Based on the pathological and laboratory findings, the diagnosis of monoclonal gammopathy of renal significance (MGRS)-associated C3GN was finally made., Conclusions: This is the first demonstration that intact monoclonal immunoglobulin (IgGλ) could act as an anti-CFH antibody and lead to MGRS-associated C3GN by activating the CAP.

Background: Densitometric quantitation using serum protein electrophoresis (SPE) is used to monitor monoclonal proteins (M-proteins) in human patients but has not been validated in the dog. Serum globulin concentrations, species-specific radial immunodiffusion (RID), and ELISAs are currently used in veterinary medicine., Objective: We aimed to compare four methods that quantify M-proteins using densitometry and biuret protein (dM-protein) measurements. We also validated the best performing method and compared it with the RID and ELISA methods for measuring canine serum M-protein., Method: Serum from six normal dogs and 83 serum samples from 46 dogs with confirmed monoclonal gammopathies were used. A spike and recovery experiment with purified monoclonal IgG and IgM, inter-run and intra-run variability, linearity under dilution, and lower limit of detection were performed. Results of commercial canine RID and ELISA kits for total class-specific immunoglobulin were compared with dM-proteins., Results: The corrected perpendicular drop gating method had <20% error for IgG/γ-globulin and IgM/β-globulin M-protein quantifications. Linearity (r > .99), intra-run CV (1.1%-2.3%), and inter-run CVs (2.0%-3.5%) were acceptable. Correlation between the RID and densitometry results ranged from r = .25 to r = .88, depending on the class. The RID result was greater than that of the biuret total protein in 26/63 (41%) IgA cases. A panel of IgG, IgA, and IgM RIDs failed to correctly identify an IgM paraproteinemia in 6/6 (100%) cases. Densitometry was not comparable with any other tested method., Conclusion: Densitometric quantitation is a valid technique for measuring M-proteins in the β- and γ-globulin regions. Immunotyping via RID using the tested kit does not appear to detect IgM. Densitometry is recommended for measuring M-proteins in canine patients., (© 2019 American Society for Veterinary Clinical Pathology.)

Background: Free light chain (FLC) quantification is the most analytically sensitive blood-based method commercially available to diagnose and monitor patients with plasma cell disorders (PCDs). However, instead of directly detecting monoclonal FLCs (mFLCs), FLC assays indirectly assess clonality based on quantifying κ and λ FLCs and determination of the к/λ FLC ratio. Often an abnormal FLC ratio is the only indication of a PCD, and confirmation by a direct method increases diagnostic confidence. The aim of this study was to develop an analytically sensitive method for direct detection of mFLCs., Methods: Patient sera (n = 167) previously assessed by nephelometric FLC quantification and immunofixation electrophoresis (IFE) were affinity enriched for IgG, IgA, and total and free κ and λ light chains and subjected to MALDI-TOF MS. Relative analytical sensitivity of these methods was determined using serially diluted sera containing mFLCs., Results: In sera with abnormal FLC ratios (n = 127), 43% of monoclonal proteins were confirmed by IFE, 57% by MALDI-TOF MS without FLC enrichment, and 87% with FLC enrichment MALDI-TOF MS. In sera with normal FLC ratios (n = 40), the FLC MALDI-TOF MS method identified 1 patient with an mFLC. Serial dilution and analysis of mFLC containing sera by IFE, nephelometry, and FLC MALDI-TOF MS demonstrated that FLC MALDI-TOF MS analysis had the highest analytical sensitivity., Conclusions: FLC immunoenrichment coupled to MALDI-TOF MS enables direct detection of mFLCs and significantly increases the confirmation of abnormal serum FLC ratios over IFE and MALDI-TOF MS without FLC enrichment, thereby providing added confidence for diagnosing FLC PCDs., (© 2019 American Association for Clinical Chemistry.)