The dark side of current analytic methods for Bence Jones Proteinuria.

OBJECTIVE: Bence Jones proteinuria (BJP) refers to monoclonal free immunoglobulin light chains detected in urine, deriving from the clonal expansion of plasma cells in the bone marrow in patients with plasma cell dyscrasias, associated with monoclonal gammopathies of uncertain origin. This review summarizes routinely diagnostic procedures to assess BJP highlighting critical steps of pre-analytical, analytical, and post-analytical phases. QUALITATIVE AND QUANTITATIVE METHODS: The best option for BJP detection is the first morning void urine sample and immunofixation electrophoresis detection technique (IFE) the recommended method, with the employment of specific polyvalent antisera. Other qualitative tests for a quick evaluation of BJP are currently available. Densitometric analysis performed on the 24-hour urine is the recommended method to quantify BJP. To overcome the 24-hour collection, it is possible to use morning urine sample and correlate the assessed value of BJP to creatininuria. In addition to the traditional ones, we here reviewed screening methods currently used to avoid false negatives and reduce the time around test (TAT), together with immunochemical quantification methods for increased sensitivity, after checking BJP by IFE. Mass spectrometry emerges as a new challenge in the determination of BJP. CONCLUSIONS: The employment of different based-assays methods may be useful for diagnostic purposes to improve the accuracy of BJP monitoring in monoclonal gammopathies.

Biochemical profile of Bence-Jones type multiple myeloma.

Multiple myeloma (MM) is a malignant tumor occurring from plasma cells that produce an abnormal monoclonal immunoglobulin - a paraprotein. A distinctive feature of Bence-Jones myeloma is the excretion of monoclonal free light chains of immunoglobulins with 24h urine, and the absence of monoclonal intact immunoglobulins secretion. Comprehensive analysis of biochemical parameters in blood serum and 24h urine in patients with Bence-Jones multiple myeloma using electrophoretic and immunoturbidimetric methods to assess their sensitivity as biomarkers. 50 patients with a morphologically confirmed diagnosis of MM of the Bence-Jones immunochemical type were examined. 28 people without oncological diseases were examinedas a control. Detection of monoclonal secretion in blood serum and daily urine was performed by immunofixation electrophoresis on the Hydrasys 2 electrophoretic system (Sebia). The determination of free light chains of immunoglobulins (FLC) was performed by the immunoturbidimetric method (Binding Site) on an Advia 1800 analyzer (Siemens). Analysis of IgG, IgA, IgM, ß2-microglobulin and C-reactive protein was performed on Cobas 6000 analyzer (Roche). The median excretion of Bence-Jones protein in 24h urine of MM patients was 0.49 g/24h (0.06-2.45 g/24h). In the blood serum, in 86% of cases, the presence of paraproteinemia, represented by κ and λ type light chains of immunogloublins was detected. At the same time, the frequency of detection of monoclonal secretion in blood serum in Bence-Jones type λ myeloma was 95.7%, which was statistically significantly higher than the frequency of detection of monoclonal secretion of type κ - 77.8%. In patients with identified paraproteinemia, Bence-Jones protein excretion in daily urine (median 0.82 g/day) was statistically significantly higher than in patients without a monoclonal component detected in blood serum (median 0.04 g/24h). The levels of FLC in blood serum obtained by immunoturbidimetry in Bence-Jones myeloma of the corresponding type were higher than the reference levels in 100% of cases. The median level of κ-FLC reached 4358 mg/l, λ-FLC - 2225 mg/l, which was statistically significantly higher than the control levels. The median concentrations of IgG, IgA and IgM in patients with Bence-Jones myeloma were statistically significantly lower than in the control group, while the medians of ß2-microglobulin and C-reactive protein were significantly higher than in the control. Our investigation showed high diagnostic efficiency of electrophoretic and immunoturbidimetric analysis of monoclonal secretion in patients with Bence-Jones MM, while FLC analysis demonstrated maximum sensitivity. Bence-Jones MM revealed biochemical signs of secondary immunodeficiency and general inflammatory syndrome.

A simple scheme for large scale purification of urine - Derived Bence Jones Kappa protein.

We have investigated and optimized purification process, suitable for industrial scale, to obtain high purity grade Bence Jones Kappa Protein ('BJK-Protein'), while preserving its physiological properties and functions. BJK-Protein was obtained from a biological waste product i.e. human urine of renal failure patients. Isolated 'BJK-Protein' was analyzed by electrophoresis, western blotting, double immunodiffusion, SEC-HPLC assay and Mass Spectrometry (MS). The relative molecular mass of 'BJK-Protein' is 23054.2 Da. Moreover, dimer forms of 'BJK-Protein' were also detected in SDS-PAGE and mass spectrum corresponding to 46054.4 Da. The results of western blotting, immunoelectrophoresis, SEC-HPLC assay, and mass spectrometry analysis indicate a high purity (>99 %) of 'BJK-Protein'. Peptide mass fingerprint analysis of 'BJK-Protein' yielded peptides that partially matches the known database sequences of kappa variable region (KV139_HUMAN) of immunoglobulin. This protein was found to be stable up to 20 months at 2-8 °C temperature and also found negative for major undesirable viral markers as well as bacterial endotoxin. With this purification approach, the cost of purified 'BJK-Protein' is significantly reduced as compared to the current market price of Kappa light chain available in international market.

Monoclonal free light chain detection and quantification: Performances and limits of available laboratory assays.

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.

Leptomeningeal and intraventricular myelomatosis manifesting an aggressive form of communicating hydrocephalus.

Leptomeningeal myelomatosis (LMM) is a fatal complication that occurs in < 1% of patients with multiple myeloma. Many patients with LMM present with neurologic symptoms referable to cranial neuropathies, while the manifestation of communicating hydrocephalus has been underrecognized. A Japanese man with Bence Jones protein-κ multiple myeloma developed fever and headache at age 54 years. He then became somnolent and went into a coma. Neuroimaging analyses identified rapidly progressive communicating hydrocephalus due to meningitis. He died 83 days after the onset of headache without any response to treatment at age 55 years. No symptoms or signs associated with cranial nerves were found during the course of illness. Postmortem examination revealed hydrocephalus and diffuse infiltration of myeloma cells into the subarachnoid space of the cerebrum, cerebellum, and brainstem. In addition, the interstitial tissue of the choroid plexuses was filled with myeloma cells. These myeloma cells were positive for CD156 and light chain κ. The Ki-67 labeling index in myeloma cells of the central nervous system (CNS) was 30-40%. Histopathological examination further revealed many myeloma cells on the surface of the lateral, third and fourth ventricles and at the area postrema of the medulla oblongata. Patients with LMM can develop an aggressive form of communicating hydrocephalus. Given that cerebrospinal fluid, produced by epithelial cells in the choroid plexuses of the ventricles, passes into the subarachnoid space through the third and fourth ventricles, myeloma cells may invade the CNS through the choroid plexuses.

Immunoglobulin D-kappa multiple myeloma in a patient with rheumatoid arthritis: a case report and review of the literature.

A 77-year-old Japanese woman with a 21-year history of seropositive, erosive rheumatoid arthritis (RA) and a 10-year history of methotrexate (MTX) therapy was admitted with malaise and mild consciousness disturbance. Laboratory data showed hypercalcemia, acute kidney injury, normocytic anaemia, and thrombocytopenia. As we first assumed drug-induced toxicity by MTX and eldecalcitol, both were discontinued and leucovorin rescue therapy and calcitonin were administered. However, her condition continued to worsen. Serum protein electrophoresis showed only a small M-peak, immunoelectrophoresis of both the serum and urine demonstrated Bence-Jones kappa (κ) type monoclonal protein without immunoglobulin heavy chain, and bone marrow examination revealed proliferation of plasma cells. We diagnosed her with Bence-Jones κ type multiple myeloma (MM) and transferred her to the department of haematology of a higher order medical institution. Conclusively, the diagnosis of immunoglobulin (Ig) D-κ type MM, a rare variant of this disorder, was determined in accordance with serum immunofixation. Several previous studies have suggested that pre-existing RA is a risk factor for MM. Although IgD MM is characterised by its clinical severity and poor prognosis compared to other subtypes, it is often misdiagnosed or mistaken as light chain type MM, as in the present case, because of the low level of IgD M-protein, resulting in delayed diagnosis. Physicians must take MM into consideration as a differential diagnosis when inactive RA patients present with inexplicable elevated calcium, renal failure, anaemia, and bone lesion symptoms and should be aware of IgD MM to establish the correct diagnosis promptly.

Historical perspectives in clinical pathology: Bence Jones protein-early urine chemistry and the impact on modern day diagnostics.

This is the third in the series of historical articles dealing with developments in clinical pathology. Bence Jones proteins are immunoglobulin light chains found in excessive quantities in urine in multiple myeloma and are believed to be one of the first tumour markers ever discovered . Dr Henry Bence Jones is credited with the discovery of this protein in 1847 that bears his name and he can also be regarded as the first chemical pathologist/clinical chemist. Since then, numerous advances and refinements have been made in the measurement and detection of urine light chain proteins which have resulted in the current sensitive serum free light chain assays used today.

κ and λ urine free light chains: a new method for quantification.

BACKGROUND: Immunofixation electrophoresis of urinary proteins, coupled with densitometric analysis, is the gold standard method for determining urinary monoclonal free light chains (FLCs), i.e. Bence Jones protein. Recently, immunochemical methods have been developed for Bence Jones protein quantification, but no such method has been widely adopted. This study evaluated a new antibody-based immunoturbidimetry method for urinary FLC quantification, using immunofixation electrophoresis as reference. METHODS: κ and λ FLCs were measured in urine specimens from 95 (training cohort) and 103 (testing cohort) patients by both immunofixation electrophoresis and immunoturbidimetry. RESULTS: There was almost perfect concordance in the training cohort between the new immunoturbidimetry assay and immunofixation electrophoresis and substantial agreement, with Cohen kappa of 0.85 and 0.75, for κ and λ FLC determination, respectively. Results were confirmed in the testing cohort, where Cohen kappa was 0.86 for κ and 0.94 for λ FLCs. The κ FLC assay had 88% sensitivity and 98%-100% specificity; the λ FLC assay had 94% and 96% sensitivity and 91% and 99% specificity in the training and testing cohorts, respectively. CONCLUSIONS: The new immunochemical method has a satisfactory performance and almost perfect agreement with immunofixation electrophoresis and gives the advantage of FLC quantification.

Nanoporous silica coupled MALDI-TOF MS detection of Bence-Jones proteins in human urine for diagnosis of multiple myeloma.

Bence-Jones protein is a biomarker in urine for multiple myeloma. Traditional methods for urine Bence-Jones protein detection are either less-sensitive or laborious. Herein, we describe a new method for the detection of urine Bence-Jones protein using nanoporous materials and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Macroporous ordered silica foams (MOSF) were used to enrich proteins in urine, and then the materials-proteins composites were analyzed by MALDI-TOF MS. Based on the presence of specific mass spectrometric signals, Bence-Jones protein can be detected for the diagnosis of multiple myeloma. Twenty-one clinical positive and twenty-seven clinical negative urine samples were analyzed by the method. High sensitivity (95.24%, 20/21) and specificity (100%, 27/27) for the diagnosis of multiple myeloma were achieved. Compared to other methods for multiple myeloma diagnosis, e.g. immunofixation electrophoresis and immunonephelometry, our approach is more rapid, economical and convenient, which can be a new choice for the clinical diagnosis of Bence-Jones protein related diseases.

When acute kidney injury in the intensive care unit is not acute tubular necrosis: A case report of κ-light chain crystalline tubulopathy
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INTRODUCTION: This case highlights the importance of getting a thorough workup for acute kidney injury before assigning a diagnosis. CASE PRESENTATION: A 68-year-old male was referred to our clinic after a recent outside hospitalization for septic knee arthritis and acute kidney injury requiring hemodialysis. He had chronic kidney disease presumed secondary to diabetes with baseline GFR 50 mL/min. He complained of fatigue and weight loss. Vital signs were within normal limits. Exam was notable for trace ankle edema, healed right knee scar, and right internal jugular hemodialysis catheter. Medications included amlodipine, aspirin, atorvastatin, furosemide, sevelamer, and cephalexin. Calculated creatinine clearance was 6 mL/min with urine output 2 L/day. Urinalysis showed 1+ protein, 2+ glucose, and fine granular casts. Clinical impression was ischemic acute tubular necrosis in recovery phase. However, when he did not improve and continued requiring dialysis, further workup showed elevated serum κ free light chains and urine Bence-Jones protein. Renal biopsy showed κ light chain crystalline tubulopathy, interstitial inflammation, and extensive fibrosis. Subsequent bone marrow biopsy showed 15% κ-restricted plasma cells. Multiple myeloma was diagnosed, and chemotherapy initiated. With decrease in κ light chain burden, kidney function improved, and patient was able to come off dialysis. CONCLUSION: This case describes a rare presentation of κ light chain crystalline tubulopathy and illustrates the value of a comprehensive evaluation for acute kidney injury to enable prompt diagnosis and therapy.
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[Difficulties evaluating hematological response in patients with multiple myeloma and dialysis - dependent renal impairment].

AIM: to determine serum free light chains (FLC) level by patients with multiple myeloma (MM) and dialysis - dependent renal impairment in which the amount Bence Jones (BJ) protein in the urine met the criteria of hematological response. PATIENTS AND METHODS: This study included 13 MM with dialysis - dependent renal impairment patients (estimated glomerular filtration rate < 10 ml/min), whose urine BJ protein content was less than 200 mg/day after antimyeloma therapy (including 11 patients whose urine BJ protein content was less than 100 mg/day). RESULTS: The median serum concentration of monoclonal FLC was 608.7 (298-8380) mg/l. Thus, with trace amounts BJ protein in the urine serum content monoclonal FLC varied 28 times with the same degree of severity of renal failure. In patients with oliguria serum SLC content was significantly higher than in normal diuresis (1109 and 307 mg/L; p.

The FLC dimer with lambda type may false-migrate to the position of "albumin" band by urine protein electrophoresis on Sebia agarose gel-based detection system.

BACKGROUND: Monoclonal free light chains (FLC) commonly exist in monomeric or dimeric forms but rarely as larger molecules. Little is known about whether polymeric molecules can affect urine protein electrophoresis (UPE) results. METHODS: Urine samples were collected from 72 multiple myeloma (MM) patients with Bence Jones protein (BJP). Urine protein and immunofixation electrophoresis were analyzed on Sebia SDS "agarose" gel electrophoresis system (SDS-AGE), and immunoglobulin free light chains were measured on the BNII nephelometric assay. RESULTS: A type of disulfide-bound FLC dimer shows a pattern shift to the position of the "albumin" band in urine protein electrophoresis in multiple myeloma (MM) patients according to the Sebia agarose gel-based detection system, which was validated by immunofixation, SDS-PAGE, and mass spectrometric methods. Similar cases were found in 21 (29.17%) of 72 MM patients with BJP, and 19 (90.5%) of 21 patients were the lambda type. CONCLUSIONS: These results indicate that BJP with lambda type has a strong tendency to abnormally migrate, which may increase the risk of misinterpretation of protein electrophoresis in clinics. Thus, when the urine protein electrophoresis is inconsistent with the result by nephelometric method, urine protein electrophoresis needs to be repeated on the deduced condition to confirm the essence of the originally identified "albumin."

A historical perspective on milestones in multiple myeloma research.

The first well-documented case of multiple myeloma was reported in 1844 by Samuel Solly. In this article, the author presents a historical review of the disease. In particular, the review is focused on the main steps, including the definition of Bence Jones proteinuria, the characterization of tumoral plasma cells and serum globulins, and the fundamental contribution of Jan Waldenstrom. Finally, treatment of multiple myeloma, as well as the development of new agents, is discussed.

Kinetic stability and sequence/structure studies of urine-derived Bence-Jones proteins from multiple myeloma and light chain amyloidosis patients.

It is now accepted that the ability of a protein to form amyloid fibrils could be associated both kinetic and thermodynamic protein folding parameters. A recent study from our laboratory using recombinant full-length (encompassing the variable and constant domain) immunoglobulin light chains found a strong kinetic control of the protein unfolding for these proteins. In this study, we are extending our analysis by using urine-derived Bence Jones proteins (BJPs) from five patients with light chain (AL) amyloidosis and four patients with multiple myeloma (MM). We observed lower stability in κ proteins compared to λ proteins (for both MM and AL proteins) in agreement with previous studies. The kinetic component of protein stability is not a universal feature of BJPs and the hysteresis observed during refolding reactions could be attributed to the inability of the protein to refold all domains. The most stable proteins exhibited 3-state unfolding transitions. While these proteins do not refold reversibly, partial refolding shows 2-state partial refolding transitions, suggesting that one of the domains (possibly the variable domain) does not refold completely. Sequences were aligned with their respective germlines and the location and nature of the mutations were analyzed. The location of the mutations were analyzed and compared with the stability and amyloidogenic properties for the proteins in this study, increasing our understanding of light chain unfolding and amyloidogenic potential.

Clinical Presentation of Tubulointerstitial Nephritis Caused by Amyloid Light-chain Amyloidosis in a Patient with Sjögren's Syndrome.

We report a 70-year-old woman with Sjögren's syndrome who had severe renal dysfunction with mild proteinuria and elevated urinary low-molecular-weight proteins. Based on these clinical presentations, interstitial nephritis due to Sjögren's syndrome was strongly suspected. Unexpectedly, renal pathology revealed amyloid light-chain (AL) lambda-type depositions predominantly in the vasculatures with severe tubulointerstitial damage. Concentrated urine immunofixation was positive for Bence Jones lambda-type monoclonal proteins. Given the involvement in other organs, systemic AL amyloidosis was diagnosed. The patient underwent chemotherapy, but hemodialysis was ultimately instituted. It should be remembered that renal amyloidosis occurs as a clinical presentation of interstitial nephritis.

Clinicopathological significance of monoclonal IgA deposition in patients with IgA nephropathy.

BACKGROUND: Clinicopathological significance of monoclonal IgA deposition and its relation to bone marrow abnormalities in IgA nephropathy (IgAN) remains unclear. METHODS: We retrospectively investigated the prevalence and clinicopathological significance of monoclonal IgA deposition in 65 patients with IgAN. Serum-free light chain ratio, and urinary Bence Jones protein were also measured. RESULTS: Thirty-nine percent of patients were men, median age was 40 and median observation period was 31 months. Five patients (Group M) showed monoclonal IgA lambda deposition and one showed monoclonal IgA kappa deposition. Fifty-nine patients (Group P) showed polyclonal IgA deposition. There were no significant differences in the degree of proteinuria, hematuria and renal function between Group M and Group P. Total protein and albumin were significantly lower in Group M than in Group P. According to the Oxford classification, the percentage of patients with M1 was significantly higher in Group M than in Group P. One patient in Group P showed serum monoclonal IgG lambda. No patient showed abnormal serum-free light chain ratio. Seventy-five percent in Group M and 42 % in Group P were treated with steroid. Three patients in Group P progressed to end-stage renal disease (ESRD). The frequency of disappearance of proteinuria or hematuria and progression to ESRD was not different between the groups. CONCLUSIONS: The prevalence of monoclonal IgA deposition was 9.2 %. Although some parameters differed between the groups, renal outcome were similar. Thus, IgAN with monoclonal IgA deposition seems not to be different entity from those with polyclonal IgA deposition.