Kappa light chain nephropathy

Summary Percutaneous renal biopsies from 4 patients with clinically unsuspected kappa light chain nephropathy were studied using light, immunofluorescence, and electron microscopy. The diagnosis in each case was established by demonstrating monoclonal kappa light chain deposits in basement membranes and basement membrane-like structures of glomeruli, tubules, and blood vessels by immunofluorescence microscopy. Characteristic electron dense deposits occurred in every case but the intensity and distribution of electron densitites did not correlate with the immunofluorescence findings. When light chain aggregation occurred, as evidenced by the distribution of electron dense deposits, it was proportional to the amount of basement membrane-like material as if these immunoglobulins had a particular affinity for structures chemically related to basement membranes. Although active tubulointerstitial lesions were prominent in all biopsies, there was considerable variation in glomerular pathology with only 1 case exhibiting the typical nodular glomerulosclerosis. Correlation of the light, immunofluorescence, and electron microscopic findings in these cases suggests that the pathogenesis of kappa light chain nephropathy is related to light chain nephrotoxicity directed to basement membrane-like structures with subsequent alterations in hemodynamics and structural renal damage.     

Kappa light chain nodular glomerulosclerosis with conspicuous crescent formation and tubulointerstitial injury. Report of a case.

We describe a 39-year-old man who developed kappa light chain nodular glomerulosclerosis with superimposed conspicuous crescent formation and extensive tubulointerstitial injury. The clinical picture was characterized by nephrotic syndrome and rapidly progressive glomerulonephritis. Incessantly progressive loss of renal function culminated in irreversible renal failure 7 weeks after initial manifestations of renal insufficiency. The patient has since been maintained on thrice weekly hemodialysis with chemotherapy for five years. At the time of pathologic diagnosis by renal biopsy, there was no evidence of multiple myeloma, and no serum M-component or Bence-Jones proteinuria was detected. An initial bone marrow aspirate revealed the presence of 0.6% atypical lymphocytes as the sole abnormality, although these were later identified as atypical plasma cells. These cells had also infiltrated the renal interstitium. Crescentic kappa light chain nodular glomerulosclerosis lacking evidence of plasma cell dyscrasia should be included in the differential diagnosis of rapidly progressive glomerulonephritis.     

Serum free light chain analysis in multiple myeloma and plasma cell dyscrasias

After the development of a reliable method to detect free light chains in serum, several investigations have been conducted to explore their importance in plasma cell dyscrasias (PCD). Detection of monoclonal proteins is very important in the diagnosis and management of PCD, which include a broad spectrum of diseases such as multiple myeloma and also benign, premalignant disorders like monoclonal gammopathy of undetermined significance. The aim of this article is to summarize the recent studies and to highlight the importance of free light chain analysis in the diagnosis of PCD, its prognostic value and role in the management of this group of diseases.     

Serum free light chain analysis in multiple myeloma and plasma cell dyscrasias

After the development of a reliable method to detect free light chains in serum, several investigations have been conducted to explore their importance in plasma cell dyscrasias (PCD). Detection of monoclonal proteins is very important in the diagnosis and management of PCD, which include a broad spectrum of diseases such as multiple myeloma and also benign, premalignant disorders like monoclonal gammopathy of undetermined significance. The aim of this article is to summarize the recent studies and to highlight the importance of free light chain analysis in the diagnosis of PCD, its prognostic value and role in the management of this group of diseases.     

Immunoquantitation of free light chain immunoglobulins: applications in multiple myeloma.

A single radial immunodiffusion (RID) assay for the free lambda (lambda) and kappa (kappa) light chain (LC) immunoglobulins was developed for study of clinical samples of serum, urine, and bone marrow of patients with multiple myeloma. Using highly specific rabbit anti-LC sera, we were able to quantitate: (a) free serum LC after fractionating the serum sample using an Amicon ultrafiltration chamber equipped with an XM100A diaflow membrane and an 125I-LC standard for calculating filtration efficiencies, (b) directly, Bence Jones (BJ) proteins in the urine, and (c) the in vitro LC synthesis by myeloma plasma cells obtained from bone marrow aspirates. The median values of free LC levels in sera (n = 12), urines (n = 25), and marrow culture synthetic rates (n = 17) were 116.2 mg/dl, 0.775 g/day and 15.3 pg/plasma cell/day, respectively. These data were useful in initial evaluation of patients and serial follow-up studies. The assays have also been of use in our research on the determination of total body tumor mass in patients with BJ multiple myeloma.     

Bone marrow lambda-type light chain crystalline structures associated with multiple myeloma

Summary A 58-year-old man showed bone marrow crystalline structures associated with a lambda light chain producing multiple myeloma. Analysis and processing of electron images clearly displayed the periodic structure of the crystals. Immunochemistry suggested that they contained the whole or a fragmented constant portion of immunoglobulin.     

Systemic kappa light chain deposition and amyloidosis in multiple myeloma: novel morphological observations

Light and transmission electron microscopic studies as well as immunohistochemical investigations were performed on a case of multiple myeloma in a 40-year-old female with systemic kappa light chain deposition. The latter took the form of extensive deposits in the liver, spleen and bone marrow. Amyloid was not found in these deposits, although it was present in the wall of branches of the portal vein. Conversely, amyloid but not light chain deposition was found in the tongue, synovial membrane from the knee and myocardium. The kidney was the only organ to show both amyloid and light chain deposits intimately associated with each other in and around tubules and collecting ducts. Ultrastructurally the light chain deposits were seen to be biphasic, having two granular components of different electron density. In the spleen and bone marrow, but not in the liver, the kappa light chain deposits were surrounded by multinucleated giant cells. This is the first report of light chain deposition disease associated with a foreign body type of giant cell reaction. The morphological variability of organ involvement suggests that the molecular structure and conformation of the deposited light chains are heterogeneous and may reflect a broad spectrum of metabolism of these deposits in various organs.     

Electrophoretic distribution of Kappa and Lambda immunoglobulin light chain determinants in serum and cerebrospinal fluid in multiple sclerosis

The electrophoretic distribution of Kappa and Lambda light chain antigenic determinants were studied in cerebrospinal fluid (CSF) and serum from cases with abnormal Immunoglobulin G patterns on agar gel electrophoresis of CSF. Electrophoretically homogeneous immunoglobulin fractions containing an excess of either Kappa or Lambda determinants were found in CSF but not in serum. The findings indicate the production of monoclonal immunoglobulins within the central nervous system in multiple sclerosis.     

Adult Fanconi syndrome in kappa light chain myeloma

Distinctive morphological features in both the marrow infiltrate and the kidney were seen in a 52-year-old woman with kappa light chain-producing plasma cell myeloma, diagnosed on the basis of multiple osteolytic lesions, the presence of atypical plasma cells in the bone marrow, and monoclonal immunoglobulin production as demonstrated by immunoperoxidase staining on marrow sections. Large focal collections of histiocytes in the bone marrow and the renal proximal tubular epithelium had abundant glassy cytoplasm. Characteristic crystalline inclusions were seen ultrastructurally in both types of cells. It is believed that these crystalline deposits are lysosomal inclusions composed of altered kappa light chains taken up by these cells. The renal changes were entirely different from those of myeloma kidneys and were associated with proximal tubular dysfunction of adult Fanconi syndrome without distal tubule abnormality.     

Kappa immunoglobulin light chain gene rearrangement in a T-lineage chronic lymphocytic leukemia

Until recently, only B-lineage lymphoid cells were observed to rearrange kappa immunoglobulin light chain genes. The authors examine peripheral blood mononuclear cells from a patient with chronic lymphocytic leukemia. More than 90% of these cells bound T-lymphocyte specific antibodies, failed to bind B-lymphocyte specific antibodies, had rearranged T-cell receptor beta-chain genes and had retained immunoglobulin heavy chain genes in the germline configuration. Despite these T-lineage markers, the majority of these cells had rearranged kappa immunoglobulin light chain genes. This provides the first conclusive evidence for rearranged kappa genes in malignant T-lineage cells and warns that gene rearrangement studies alone cannot indicate tumor cell lineage. To detect T-lineage cells that rearrange immunoglobulin genes, multiple immunophenotypic and genotypic parameters must be evaluated. These cells may provide important models to study how normal and malignant cells rearrange lymphocyte receptor genes.     

Kappa: lambda light chain ratio in IgG eluted from rheumatoid arthritis synovium

The light chain ratio in IgG eluted from rheumatoid arthritis synovial membrane was studied using quantitative immunodiffusion. The ratio obtained in synovial IgG was different from that of IgG in peripheral blood. In several instances a marked domination of one type light chain was noted in the eluted IgG, which also showed a limited electrophoretic dispersion on immunoelectrophoresis. This suggests that synovial IgG in rheumatoid arthritis is antibody, and not derived non-specifically from the immunoglobulin pool. Lambda type light chains dominated over kappa type in most eluates, suggesting preferential involvement of cells producing lambda type molecules.     

High prevalence of immunoglobulin light chain gene aberrations as revealed by FISH in multiple myeloma and MGUS

Multiple myeloma (MM) is a malignant B‐cell neoplasm characterized by an uncontrolled proliferation of aberrant plasma cells in the bone marrow. Chromosome aberrations in MM are complex and represent a hallmark of the disease, involving many chromosomes that are altered both numerically and structurally. Nearly half of the cases are nonhyperdiploid and show IGH translocations with the following partner genes: CCND1, FGFR3 and MMSET, MAF, MAFB, and CCND3. The remaining 50% are grouped into a hyperdiploid group that is characterized by multiple trisomies involving chromosomes 3, 5, 7, 9, 11, 15, 19, and 21. In this study, we analyzed the immunoglobulin light chain kappa (IGK, 2p12) and lambda (IGL, 22q11) loci in 150 cases, mostly with MM but in a few cases monoclonal gammopathy of undetermined significance (MGUS), without IGH translocations. We identified aberrations in 27% (= 40 patients) including rearrangements (12%), gains (12%), and deletions (4.6%). In 6 of 18 patients with IGK or/and IGL rearrangements, we detected a MYC rearrangement which suggests that MYC is the translocation partner in the majority of these cases. © 2014 Wiley Periodicals, Inc.     

Phagocytic, lambda light chain, plasma cell myeloma

A case of phagocytic, lambda light chain, plasma cell myeloma was characterized by its clinical, morphologic, cytochemical, immunologic, and cell kinetic features. A 40-year-old man presented with Coombs-negative hemolytic anemia, hepatosplenomegaly, lytic bone lesions, lambda light chain monoclonal gammopathy, and infiltration of the bone marrow by dysplastic plasma cells, 10% of which demonstrated phagocytosis of erythroid cells. Electron microscopy demonstrated myeloma cells with prominent cytoplasmic microfilaments and erythroid cells in intracytoplasmic vacuoles. The myeloma cells did not phagocytose staphylococci in vitro. Phagocytic and nonphagocytic myeloma cells were tartrate-sensitive, acid-phosphatase positive, alpha-napthyl butyrate esterase negative, and did not form E rosettes or EAox(IgG) rosettes. The tumor cells were Tdt, Ia antigen, and SIg negative. Immunofluorescent staining for cytoplasmic light chains showed a monoclonal lambda pattern in nonphagocytic myeloma cells, and a probable monoclonal lambda pattern in phagocytic myeloma cells. These findings characterize the neoplasm as a monoclonal proliferation of differentiated plasma cells with the capability of erythrophagocytosis. Erythrophagocytosis by myeloma cells may have been responsible for the hemolytic anemia. The tritiated thymidine labeling index (LI%) was high (8%), suggesting a poor prognosis, despite a dramatic initial response to chemotherapy.     

Quantitation of light chain synthesis in myeloma × spleen cell hybrids and identification of myeloma chain loss variants using radioimmunoassay

A radioimmunoassay specific for the MOPC 21 kappa (K) myeloma chain of NSI and X63 myeloma × spleen cell hybrids was used to study light chain secretion in myeloma-hybrid lines. The M1 series of rat spleen cell × NSI mouse myeloma hybrid lines was chose to illustrate the application of the radioimmunoassay for K chain quantitatation and identification of K chain loss variants. Most of these secrete H (specific heavy), L (specific light), and K (myeloma kappa) chains, i.e., are HLK lines. Assays specific for rat L chain and mouse K chain showed that the ratio of L/K chain secreted by 6 different hybrid HLK lines ranged from 1.1 to 12.4. Using the rapid radioimmunoassay screening procedure, HL clonal variants which had lost K chain secretion were isolated at a frequency of ～10^?2 and characterized. K chain loss was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of radiolabelled secreted products. Stability of one HL line and its HLK parent was examined during 9 months of growth in vitro. The HL line remained stable, while antibody secreted by the HLK line became inactive, apparently due to overgrowth by clonally dominant HK cells which no longer secreted specific L chains. The radioimmunoassay appears to detect MOPC 21 k chain variable region determinants. Therefore, although used here with rat-mouse hybrids, it should also be possible to use the assay to obtain mouse-mouse variant hybrid lines secreting antibody of improved homogeneity.     

Primary structure of a monoclonal kappa chain in myeloma with light chain deposition disease.

Previous data suggest that structural abnormalities of immunoglobulin light chains may be responsible for non-amyloid light chain deposition disease (LCDD). We report on the complete primary sequence deduced from complementary (c)DNA analysis of a normal-sized kappa chain in a case of myeloma-associated LCDD. The patient's urine contained a kappa type Bence-Jones protein made of monomers and dimers of an unglycosylated kappa chain. The bone marrow myeloma cells contained intracellular kappa and gamma chains by immunofluorescence. Biosynthesis experiments showed the production of normal-sized gamma chains and of kappa chains with the same apparent molecular mass (Mr) in SDS gels as the urinary kappa chain (26,000-27,000). These kappa chains were secreted as assembled IgG molecules and as a large excess of free monomers and dimers. The complete sequence of two identical cDNA clones derived from a normal-sized kappa messenger RNA indicated that this kappa chain belonged to the rare V kappa IV subgroup. The kappa mRNA had an overall normal structure made up of the V kappa IV sequence rearranged to J kappa 1 and followed by a normal constant exon of the Km(3) allotype. The variable region differed from the V kappa IV-J kappa 1 germline sequence by 17 amino acid substitutions. The peculiar sequence of the variable region of this kappa chain of a rare subgroup might relate to its tissue deposition.     

Immunoglobulin heavy/light chain analysis enhances the detection of residual disease and monitoring of multiple myeloma patients

Aim

To evaluate the clinical utility of incorporating a novel heavy/light chain immunoassay (HLC) into the existing methods for the assessment of multiple myeloma (MM) patients.

Methods

Convenience sera samples from 90 previously treated IgG and IgA MM patients in different disease stages were analyzed. The study was conducted in Clinical Hospital Center Zagreb between 2011 and 2013. The collected sera were analyzed by standard laboratory techniques (serum protein electrophoresis, quantification of total immunoglobulins, serum immunofixation, serum free light chain [FLC] assay) and HLC assay.

Results

HLC ratios outside the normal range were found in 58 of 90 patients, including 28 out of 61 patients with total immunoglobulin measurements within the normal range and 5 out of 23 patients in complete response. Both elevated HLC isotype level and abnormal HLC ratio correlated with the parameters of tumor burden, including percentage of plasma cells in the bone marrow (P < 0.001 and P = 0.002, respectively) and an abnormal serum FLC ratio (for both P < 0.001). In addition, abnormal HLC isotype level correlated with serum beta-2-microglobulin level (P = 0.038). In terms of prognosis, abnormal HLC isotype level and abnormal HLC ratio were significantly associated with shorter overall survival (P < 0.001 and P = 0.002, respectively). Interestingly, suppression of the uninvolved (polyclonal) isotype pair, but not other non-myeloma immunoglobulin isotypes, was also associated with a shorter overall survival (P = 0.021). In a multivariate analysis, an abnormal HLC ratio and β₂-microglobulin level >3.5mg/L were independent risk factors for survival.

Conclusion

The new HLC assay has greater sensitivity in detecting monoclonal protein, correlates with tumor burden markers, and affects patients'' outcome.Hematological malignancy multiple myeloma is characterized by the proliferation of monoclonal plasma cells in the bone marrow, which usually leads to the secretion of monoclonal intact immunoglobulins (Ig), free light chains (FLC), or both, into the serum. Consequently, the measurement of monoclonal proteins is integral to diagnosing multiple myeloma, monitoring of response to treatment, and detecting relapse (1-3). Conventional methods rely principally on serum electrophoresis together with either urine electrophoresis for the detection of FLC M-proteins or nephelometric quantification of total Igs for intact Ig paraprotein measurement. However, these standard techniques often do not have the required sensitivity or do not correlate with the patient’s clinical status (4-7).The ability to detect monoclonal serum FLC has been substantially increased by the introduction of the serum FLC assay, improving the diagnosis, monitoring, and prognosis of a number of plasma cell dyscrasias (8,9). Still, a number of problems associated with the detection of monoclonal intact Igs persist. Serum Ig concentrations can change for ≥50% with fluctuations in blood volume and/or hematocrit (10). In the case of monoclonal IgGs, the serum concentration can be also influenced by altered metabolism due to recycling of IgG by the neonatal Fc receptors (11-13). Furthermore, monoclonal proteins, in particular IgA paraproteins, may not be accurately quantified by serum protein electrophoresis (SPE) due to co-migration with other serum proteins (14,15). Finally, one of the major limitations of measuring total Igs is the inability to distinguish between the monoclonal component and polyclonal Ig background.These problems can be addressed by a recently developed heavy/light chain (HLC) immunoassay. Using specific antibodies targeted to junctional epitopes of the heavy and light chains of Ig molecules, HLC immunoassay separately quantifies different light chain types of each Ig class (IgGκ, IgGλ, IgAκ, IgAλ, etc), thus providing accurate quantification of both the involved and uninvolved components of the patient''s affected Ig isotype. The ratio of the monoclonal and polyclonal Igs of the same isotype (IgGκ/IgGλ, IgAκ/IgAλ) provides a sensitive measure of monoclonality, while minimizing the influence of changes in blood volume/hematocrit and the effect of IgG recycling (16,17).Previous studies using this novel assay in specific, controlled patient cohorts found the HLC ratio to be useful for screening, monitoring, and risk stratification of patients with multiple myeloma, but also with other monoclonal gammopathies, such as monoclonal gammopathy of undetermined significance (MGUS) and amyloid light-chain (AL) amyloidosis (18-20). The aim of this study was to evaluate the ability of the new assay – HLC isotype measurements – to detect monoclonal protein (ie, residual disease) in previously treated multiple myeloma patients and to determine whether these patients can benefit from adding the new assay into a routine assessment.