Immunofluorescence staining for immunoglobulin heavy chain/light chain on kidney biopsies is a valuable ancillary technique for the diagnosis of monoclonal gammopathy-associated kidney diseases.

Heavy chain/light chain (HLC) antibodies target conformational epitopes at the junctions of the heavy chain and light chain constant regions (CH1 and CL) of serum IgGκ, IgGλ, IgAκ, IgAλ, IgMκ, and IgMλ to provide quantitation of intact HLC pairs. Here, we developed an HLC tissue immunofluorescence protocol to test if it can complement conventional immunofluorescence in the diagnosis of monoclonal gammopathy-associated kidney diseases. HLC immunofluorescence was performed on archived frozen tissue of 104 kidney biopsies. The sensitivity and specificity of HLC immunofluorescence was confirmed by testing cases of lupus nephritis, other polyclonal immunoglobulin nephropathies, and light chain nephropathies (light chain amyloidosis and deposition disease). Testing of ten cases of the IgG variant of proliferative glomerulonephritis with monoclonal immunoglobulin deposits excluded monoclonal deposits in two by revealing positivity for IgGκ and IgGλ. Testing of 12 cases of monotypic IgA nephropathy excluded monoclonal deposits in six by revealing staining for IgAκ and IgAλ. Testing of six cases of monotypic fibrillary glomerulonephritis excluded monoclonal deposits in three by revealing positivity for IgGκ and IgGλ. None of 14 cases of glomerulonephritis in which HLC immunofluorescence unmasked polytypic deposits were associated with a serum or urine monoclonal immunoglobulins matching the conventional immunofluorescence results. HLC immunofluorescence outperformed paraffin immunofluorescence and IgG subclass staining in 10/13 (77%) of cases. Testing of 18 cases of cryoglobulinemic glomerulonephritis showed better correlation with serum cryoprecipitate immunofixation than conventional immunofluorescence with regards to the type of cryoglobulin in 47% of cases. Thus, HLC immunofluorescence is a valuable ancillary technique in kidney pathology for the diagnosis of monoclonal gammopathy-associated nephropathies, and could be utilized to confirm or exclude the monoclonal nature of deposits.

A new risk model to predict time to first treatment in chronic lymphocytic leukemia based on heavy chain immunoparesis and summated free light chain.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is frequently accompanied by immune dysregulation. AIMS: In this multicenter prospective study, we investigated whether heavy + light chains (HLC: IgGκ, IgGλ, IgAκ, IgAκ, IgMκ, IgMλ) and IgG subclasses (IgG1, IgG2, IgG3, and IgG4) could be used as novel prognostic markers of immunoparesis in 105 treatment-naïve patients with CLL. RESULTS: Heavy + light chains immunoparesis of ≥1, ≥2, and ≥3 isotypes was evident in 74 (70%), 58 (55%), and 36 (34%) patients, respectively. Severe HLC immunoparesis was identified in 40 (38%) patients. Of the IgG subclasses, IgG1 and IgG2 were most frequently suppressed, affecting 46 (44%) and 36 (34%) patients, respectively; 63 (60%) patients had low levels of at least one IgG subclass. In multivariate analysis, severe HLC immunoparesis (hazard ratio [HR]: 36.5; P = .010) and ΣFLC ≥ 70 mg/L (HR: 13.2; P = .004) were the only factors independently associated with time to first treatment (TTFT). A risk model including these variables identified patients with 0, 1, and 2 risk factors and significantly different TTFT (P < .001). Patients with two factors represented an ultra-high-risk group with a median TTFT of only 1.3 months. CONCLUSION: The above findings demonstrate the potential for the use of HLC immunoparesis, together with sFLC measurements, as future prognostic biomarkers in CLL.

Immunoparesis defined by heavy+light chain suppression is a novel marker of long-term outcomes in cardiac AL amyloidosis.

Cardiac involvement and presenting dFLC (difference between involved and uninvolved free light chains) are independent predictors of outcome in systemic AL amyloidosis. These markers have limited prognostic utility in patients surviving the initial months following diagnosis. Here we assessed immunoparesis, as determined by novel heavy+light chain (HLC) immunoassays, as a prognostic marker for survival in AL amyloidosis. HLC measurements identified immunoparesis of at least one immunoglobulin (Ig) isotype in 145 (85%) patients; and severe immunoparesis (≥2 Ig isotypes suppressed by >50% below normal levels) in 29 (17%) patients. Median overall survival (OS) on intention to treat (ITT) analysis was 26·2 months. In the ITT cohort, dFLC >180 mg/l was associated with shorter OS (P = 0·05); whereas HLC immunoparesis was not prognostic. On a landmark analysis of 127 patients alive at 6 months, presenting dFLC was not prognostic for OS (P = 0·33) and severe HLC immunoparesis trended towards poorer survival (20·2 vs. 42·8 months; P = 0·09). In the subset of patients with cardiac involvement, severe HLC immunoparesis conferred very poor outcome (median OS 8·8 vs. 29·9 months, P = 0·007). In conclusion, severe HLC immunoparesis is an independent marker of long-term poor prognosis in AL patients with cardiac involvement. The pathophysiological significance of this observation needs further study.

Levels of uninvolved immunoglobulins predict clinical status and progression-free survival for multiple myeloma patients.

Multiple myeloma (MM) is characterized by the enhanced production of the same monoclonal immunoglobulin (M-Ig or M protein). Techniques such as serum protein electrophoresis and nephelometry are routinely used to quantify levels of this protein in the serum of MM patients. However, these methods are not without their shortcomings and problems accurately quantifying M proteins remain. Precise quantification of the types and levels of M-Ig present is critical to monitoring patient response to therapy. In this study, we investigated the ability of the HevyLite (HLC) immunoassay to correlate with clinical status based on levels of involved and uninvolved antibodies. In our cohort of MM patients, we observed that significantly higher ratios and greater differences of involved HLC levels compared to uninvolved HLC levels correlated with a worse clinical status. Similarly, higher absolute levels of involved HLC antibodies and lower levels of uninvolved HLC antibodies also correlated with a worse clinical status and a shorter progression-free survival. These findings suggest that the HLC assay is a useful and a promising tool for determining the clinical status and survival time for patients with multiple myeloma.

[Analysis of the relationship of heavy/light chain pairs of immunoglobulin (Hevylite) to the results of gel electrophoresis and nefelometric examination of serum proteins at the time of multiple myeloma diagnosis]. / Analýza vztahu sérových hladin páru tezkých/lehkých retezcu imunoglobulinu (Hevylite) k výsledkum standardní gelové elektroforézy a nefelometrického vysetrení bílkovin séra pri diagnóze mnohocetného myelomu.

BACKGROUND: The diagnostics and treatment of multiple myeloma (MM) requires precise analysis of serum immunoglobulins, which might be limited by the sensitivity of standard examination methods. Hevylite method enables quantitative analysis of heavy/light chain pairs (HLC) of normal and tumor IgG and IgA immunoglobulin and their ratio (HLC-r). The aim of the study was to assess the contribution of Hevylite method in the diagnostics of MM in comparison with nephelometry (NEF), standard protein electrophoresis (SPE), immunofixation electrophoresis (IFE) and the examination of serum free light chains (FLC) of immunoglobulin using Freelite test and heavy/light chain pairs of immunoglobulin (HLC) using Hevylite. METHODS: Using the methods Hevylite, NEF, SPE, IFE and Freelite, we examined a cohort of 134 individuals fulfilling the International Myeloma Working Group (IMWG) criteria. 96 patients were of IgG and 38 of IgA type. RESULTS: The levels of HLC-kappa (K) and HLC-lambda (L), as well as HLC-r were independent of age and gender. Abnormal HLC levels were present in 84-100%, pathological HLC-r was in 92-100% cases based on MIg isotype. We found strong positive correlation between IgG and IgA (NEF) and the sum of HLC IgG-K + IgG-L (Hevylite) (r = 0.80, p < 0.0001) and HLC IgA-K + IgA-L (r = 0.75, p < 0.0001). Very strong positive correlation was between the concentration of MIg (SPE) and the levels of HLC (Hevylite) in IgG-K (r = 0.73), IgG-L (r = 0.76), IgA-K (r = 0.70) and IgA-L (r = 0.89), p < 0,0001. Systematic difference between Hevylite vs. MIg (SPE) was confirmed by Bland-Altmann test in the case of HLC IgA-K and IgA-L (not HLC IgG-K and IgG-L), and in the correlation of HLC with IgG and IgA (NEF). The most significant correlation between SPE (patients with < 15 g/L) vs. Hevylite was found within the analysis of HLC IgG-K+ IgA-K (r = 0.85, p < 0.0001), and in the whole cohort of MM patients, i.e. IgG + IgA-kappa and lambda (r = 0.76, p < 0.0001), confirmed by Bland-Altmann test. Tight positive correlation was between HLC-r and index of monoclonality FLC-K/L in MM of IgG and IgA type MM (p < 0.0001). CONCLUSION: Hevylite method, especially the assessment of HLC-r of IgA type MM is more sensitive in comparison with SPE evaluated by NEF, and increases the diagnostic sensitivity and the extent of tumor mass examination. Despite its limitation in the case of high levels of IgG type MIg, Hevylite technique has a promising potential to enrich the standard analytic tools as it enables to assess the concentration and ratio of the levels of both tumor and physiological immunoglobulins e.g. depth of immunoparesis, valid especially in MM with low levels of MIg.

IgA kappa/IgA lambda heavy/light chain assessment in the management of patients with IgA myeloma.

BACKGROUND: Accurate quantification of immunoglobulin A (IgA) monoclonal immunoglobulins by serum protein electrophoresis (SPEP) can be difficult and can impact the assessment of response among patients with multiple myeloma (MM). Therefore, there is a need to identify new assays that better reflect disease burden and response to treatment, and correlate with patient outcome. IgA Hevylite (HLC) measures IgA kappa and IgA lambda separately and provides precise quantitative measurements of the monoclonal IgA expression and polyclonal-isotype matched suppression. In the current study, the authors assessed the usefulness of these assays in the diagnosis of IgA MM and sought to comment on the prognostic value of the assays. METHODS: A study of 157 patients with IgA MM for whom diagnostic samples were available was performed. HLC measurements were performed on a nephelometer and the results were compared with those of electrophoresis. RESULTS: All presentation sera (100 IgA kappa specimens and 57 IgA lambda specimens) were found to have abnormal IgA HLC ratios (IgA kappa median ratio: 336.2 [range, 8.2-7353] and IgA lambda ratio: 0.011 [range, 0.0003-0.45]). In comparison, SPEP bands were quantifiable in only 105 of 157 samples (67%) (median, 28.5 g/L [range, 2.2 g/L-98 g/L]). Of the total of 157 patients, 12 patients (8%) presented with oligosecretory myeloma (<10 g/L; including 4 patients with nonquantifiable SPEP bands). HLC uniquely allows for the measurement of isotype paired suppression, which was found to be associated with shortened overall survival in the current study. CONCLUSIONS: In the current study, IgA HLC ratios were found to be abnormal in all patients and the assay was able to produce quantifiable results in more MM sera than either SPEP or total IgA, potentially representing a solution to the issue of comigration and oligosecretory MM. These preliminary data require confirmation in larger prospective trials to validate the usefulness of IgA HLC.

The Current Role of the Heavy/Light Chain Assay in the Diagnosis, Prognosis and Monitoring of Multiple Myeloma: An Evidence-Based Approach.

Despite tremendous progress being made in recent years, multiple myeloma (MM) remains a challenging disease. The laboratory plays a critical role in the overall management of patients. The diagnosis, prognosis, clinical monitoring and evaluation of the response are key moments in the clinical care process. Conventional laboratory methods have been and continue to be the basis of laboratory testing in monoclonal gammopathies, along with the serum free light chain test. However, more accurate methods are needed to achieve new and more stringent clinical goals. The heavy/light chain assay is a relatively new test which can overcome some of the limitations of the conventional methods for the evaluation of intact immunoglobulin MM patients. Here, we report an update of the evidence accumulated in recent years on this method regarding its use in MM.

Serum Hevylite® assay in the differential diagnosis of patients with high suspicion of AL Amyloidosis.

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.

[Diagnostic performance of κ/λ serum free light chain ratio (Freelite® assay) and IgGκ/IgGλ ratio (Hevylite® assay) as prognostic biomarkers of the evolution of immune thrombocytopenia into a chronic disease in adult patients]. / Performance diagnostique des rapports κ/λ des chaines légères libres sériques (test Freelite®) et IgGκ/IgGλ (test Hevylite®) comme marqueurs pronostiques de chronicisation du purpura thrombopénique immunologique de l'adulte.

INTRODUCTION: Immune thrombocytopenia (ITP) is an acquired hemorrhagic disease due to antiplatelet antibodies, that will become a chronic disease in 70% of adults. Most of chronic ITP patients display clonal restriction of antiplatelet antibodies. To date, there is no biomarker able to predict the evolution of the disease. The objective of the study is to determine whether Hevylite® and/or Freelite® assays are prognostic factors for progression to chronic ITP. METHODS: This is a retrospective, monocentric, prognostic study of a biomarker, performed using frozen samples stored in a serum library. Freelite® and a Hevylite® assays were performed on the samples collected at diagnosis for adult patients with newly diagnosed ITP at the University Hospital of Poitiers between 2014/01/01 and 2017/05/01. To predict the evolution into a chronic disease, a ROC curve analysis was performed on four variables: IgGκ, IgGκ/IgGλ ratio, IgGκ - IgGλ, and κ/λ ratio. RESULTS: Thirty-two patients were included and analyzed. No patient had an abnormal κ/λ ratio. Three patients had an abnormal IgGκ/IgGλ ratio. The following variables IgGκ, IgGκ/IgGλ, IgGκ - IgGλ, and κ/λ ratio were not able to predict progression to chronic ITP in our study. CONCLUSION: This study did not reveal any prognostic value of the Freelite® and Hevylite® tests on the evolution of ITP into a chronic disease.

Abnormal Heavy/Light Chain Ratio and Matched Pair Suppression Increase Residual Disease Detection Sensitivity in Patients With Multiple Myeloma With Deep Responses.

BACKGROUND: Heavy/light chain (HLC) assay can quantify involved as well as uninvolved immunoglobulin pairs and is used to detect monoclonal proteins. PATIENTS AND METHODS: We compared the sensitivity between HLC assay and serum protein electrophoresis, serum immunofixation electrophoresis (IFE), and free light chain (FLC) assay in patients with symptomatic multiple myeloma (n = 111) whose responses were stable disease or better. RESULTS: Among patients with negative IFE and normal FLC ratios, 84.4% (38 of 45) and 80% (36 of 45) exhibited normal HLC ratios and no pair suppression, respectively (13.3% [6 of 45], moderate pair suppression and 6.7% [3 of 45], severe pair suppression). The lower the monoclonal protein levels, the more the possibility that the patients had normal HLC ratios and no matched pair suppression (both P < .000001). HLC ratios or pair suppression combined with IFE results and FLC ratios were more sensitive for detecting monoclonal proteins than were IFE results and FLC ratios alone (P = .016 and .0039, respectively). A combination of all 4 methods (IFE, FLC, HLC, and pair suppression) was far more sensitive than were IFE findings plus FLC ratios alone (P = .00024). CONCLUSION: Abnormal HLC ratios and HLC-matched pair suppression can increase the sensitivity for detecting residual disease in patients with multiple myeloma with deep responses.

Immunoglobulin heavy light chain test quantifies clonal disease in patients with AL amyloidosis and normal serum free light chain ratio.

BACKGROUND: Serum and urine immunofixation electrophoreses (SIFE/UIFE) are used for clonal detection in plasma cell dyscrasias, while serum free light chain (sFLC) testing provides quantitation of clonal disease. Up to 20% of patients with light chain (AL) amyloidosis may present with normal FLC ratio (FLCr). METHODS: We assessed the diagnostic, quantitative and prognostic potential of serum heavy light chain ratio (HLCr) in 199 untreated patients at initial evaluation. RESULTS: An abnormal HLCr was found in 37.2%, abnormal FLCr in 81.9% and positivity by SIFE/UIFE in 94% of patients. HLCr together with SIFE/UIFE identified clonality in 94% patients; the combination with FLCr yielded 100% sensitivity. An HLCr abnormality was significantly over-represented in normal compared to abnormal FLCr group (63.9% versus 31.3%). HLCr did not predict overall survival (OS) (log rank, p = 0.09), while an abnormal FLCr was associated with decreased OS (log rank, p = 0.03). The combined use of both ratios trended toward increased OS in the abnormal HLCr/normal FLCr group (log rank, p = 0.11; Wilcoxon, p = 0.04). On multivariate analysis, HLCr was not predictive of OS, whereas an abnormal FLCr was associated with shorter OS (HR = 1.7, p = 0.04). CONCLUSIONS: The HLC assay has potential as a supplemental test to quantify monoclonal protein in patients with normal FLCr results.

Benefits of new immunoglobulin-derived biomarkers for the diagnosis and follow-up of patients with dysglobulinemia.

The diagnostics and follow-up of monoclonal gammopathies such as multiple myeloma require precise analysis of the monoclonal component as well as the other immunoglobulins isotypes, which might be limited by the sensitivity of standard laboratory methods. New serum biomarkers were developed for routine practice in the last decades, such as the free light chain assays and more recently the heavy/light chain assays. Studies have shown that serum free light chain measurement was useful in the identification and follow-up of pauci or nonsecretory myeloma, free light-chain multiple myeloma and AL amyloidosis. It is also an important prognostic marker for monoclonal gammopathy of undetermined significance and AL amyloidosis progression. Hevylite method enables quantitative analysis of heavy/light chain pairs of IgG, IgA and IgM immunoglobulins. This technique has a promising potential to enrich the standard analytic tools as it enables to assess the concentration and ratio of the levels of both tumor and physiological immunoglobulins (heavy/light chain pair suppression), which is not possible with serum protein electrophoresis or global quantitative analysis of immunoglobulin isotypes. This review includes the latest International myeloma working group recommendations and key data presented at the Euromedlab convention in June 2015 Paris regarding serum free light chain and heavy/light chain assays in the biological monitoring of dysglobulinemia.

Diagnostic Advances in Multiple Myeloma.

There have been several advances in the diagnosis of multiple myeloma (MM) in recent years. Serum free light chains have improved the ability to diagnose light chain MM; however, there are still difficulties in the serologic diagnosis of MM in some cases, particularly IgA MM. A novel heavy/light chain assay is able to improve the accuracy of diagnosis in these cases. Free light chains may also improve the diagnosis of extramedullary disease in difficult cases such as disease involving the central nervous system, pleura, or ascites. Advances in imaging such as whole body low-dose computed tomography (CT) whole body magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) have improved sensitivity in identifying lytic bone lesions, which would enable earlier treatment, and monitoring of osseous disease particularly in non- or oligosecretory disease. New techniques such as fused PET/MRI may further enhance the diagnosis of both bone lesions and extramedullary disease.

Biological variation of immunoglobulin heavy chain-light chain pairs in serum.

BACKGROUND: Assays for immunoglobulin heavy chain-light chain (HLC) pairs called Hevylite® have recently been developed. These assays can be useful in patients with hard to interpret serum protein electrophoresis peaks. Measurement of the biological variation of clinical laboratory tests can help clinicians better interpret laboratory results. METHODS: Serum samples were collected from 15 healthy donors and assayed with IgAκ, IgAλ, IgGκ and IgGλ Hevylite. The coefficients of the within-subject and between-subject biological variation, index of individuality (II), number of samples (n) required to determine the homeostatic setting points (HSP) and reference change values (RCV) were calculated. RESULTS: The coefficients of the within-subject biologic variation were all less than the between-subject biological variation. The II for all the assays and their κ/λ ratios were near or <0.6. The RCV ranged from 17 to 41%. The number of measurements to determine the HSP for an individual was 1 for the HLC ratios and between 2 and 9 for the individual isoforms. CONCLUSIONS: II indicates it is better to use the patient's individual results rather than population based reference values, fewer measurements are required to determine the HSP for the HLC ratios than the individual isoforms and the RCV can now be used to aid in interpretation.

[Evaluation of the new Hevylite™ IgA assay for the diagnosis and follow-up of monoclonal gammopathies]. / Évaluation du nouveau test Hevylite™ IgA dans le diagnostic et le suivi des gammapathies monoclonales.

Multiple myeloma diagnosis and follow-up are based on monoclonal protein measurement. The estimation of monoclonal immunoglobulin production requires serum protein electrophoresis, immunoelectrophoresis and free light chain assay. However these classical assays have some limitations. Hevylite™ IgA (Binding Site) is a new nephelometric/turbidimetric assay allowing the IgA κ and IgA λ measurement. The aim of this study was to determine the performance of this assay, for the diagnosis and follow-up of myeloma patients at different stages. Sixty seven frozen sera from 26 patients were assayed. Total IgA, IgA κ, IgA λ concentrations, serum protein electrophoresis and serum immunofixation were performed at diagnosis and during follow-up. All myeloma patients had an abnormal IgA κ/IgA λ ratio at diagnosis. During disease monitoring, the IgA κ or IgA λ concentrations correlated well with the electrophoretic estimation of the monoclonal spike and the values of total IgA. Hevylite™ test was more sensitive than serum protein electrophoresis and provided numerical and reproductible assessment of the monoclonal and non-monoclonal isotype. The IgA κ/IgA λ ratio allowed early prediction of disease relapse. Hevylite™ is an interesting assay especially when the monoclonal IgA comigrates on electrophoresis with normal proteins making impossible a reliable densitometric estimation. Hevylite™ might become an important assay in the biological exploration of gammopathies.