scholarly journals The occurrence of disulphide bonds in purified clathrin light chains

1989 ◽  
Vol 257 (3) ◽  
pp. 775-781 ◽  
Author(s):  
P Parham ◽  
F M Brodsky ◽  
K Drickamer
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
Reduced Form ◽  
Light Chains ◽  
Cysteine Residues ◽  
Free Light Chains ◽  
Clathrin Heavy Chain ◽  
Disulphide Bonds ◽  
Antigenic Properties ◽  
Reduced Forms

Three forms of clathrin light chain contain two cysteine residues. These are the predominant brain-specific forms of LCa and LCb and the non-brain form of LCb. After purification in the absence of thiols they contain intramolecular disulphide bonds. The reduced and the oxidized forms show differences in electrophoretic mobility, explaining the variable and heterogeneous patterns observed on electrophoresis. Accessibility of the thiol groups in the free light chains is greater than when they are associated with the heavy chain. In contrast the cysteine residues of the clathrin heavy chain are completely inaccessible in the absence of denaturants and are not found in disulphide bonds. The antigenic properties of the oxidized and the reduced forms of the clathrin light chains are similar, as is their capacity to bind to the clathrin heavy chain. After isolation in the presence of 10 mM-iodoacetamide, the light-chain cysteine residues are fully alkylated. The results are consistent with the reduced form being the native state and the light-chain disulphide bonds an artifact of isolation.

Biclonal Multiple Myeloma with Monoclonal Free IgG3 Heavy Chain and kappa Free Light Chains.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4768-4768
Author(s):  
Alex G. Richter ◽  
Stephen Harding ◽  
Steve Rimmer ◽  
Guy Pratt ◽  
Aarnoud Huissoon ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Western Blot ◽  
Heavy Chain ◽  
Light Chain ◽  
Lymphoproliferative Disorder ◽  
Plasma Cells ◽  
Light Chains ◽  
Cell Transplant ◽  
Free Light Chains ◽  
Night Sweats

Abstract Background: Heavy chain disease (HCD) is a rare lymphoproliferative disorder characterized by a monoclonal heavy chain (HC) unattached to a light chain (LC). IgGHCD or γHCD typically presents as a lymphoproliferative disorder with lymphadenopathy and hepatosplenomegaly. Myeloma has been described associated with γHCD but only with a second intact Ig paraprotein. This report describes a unique presentation of multiple myeloma with monoclonal free γ3HC and kappa free light chains. Case: A 34 year old gentleman presented with mild persistent neutropenia following two episodes of pneumonia, 18 months previously. He admitted to persistent night sweats but no other significant history. Baseline investigations revealed a mild anaemia, neutropenia and a large IgG paraprotein with no associated light chain. Bone marrow aspirate and trephine confirmed myeloma. The patient was treated with cyclophosphamide, thalidomide and dexamethasone and has had a very good partial remission. He is awaiting a sibling allogeneic peripheral blood stem cell transplant. Investigations and results: Serum Electrophoresis confirmed a large IgG paraprotein (23g/l) with no associated light chain in the serum and identified as γ3 subclass by radial immunodiffusion. Western blot showed the γ3HC was truncated with a large deletion. Markedly elevated free kappa (κ) LC (503.58 mg/l [3.30–19.4]) were found in the serum with gross skewing of the kappa/lambda ratio. Urine electrophoresis revealed separate γHC and κ LC paraproteins. Western blot of the fractionated urine protein demonstrated different sized κLC aggregates. Flow cytometry of the marrow aspirate revealed an unusual staining pattern; CD5,19,38,45+ve and CD20,22,23,34,56,138 –ve plasma cells. Cytoplasmic staining revealed 2 distinct populations of plasma cells, the first producing γ3HC and the second only free κLC. Cytogenetics and FISH analysis for 14q, p53 and c-myc abnormalities were normal. Discussion: This is the first description of a Biclonal Myeloma with separate plasma cell populations producing γ3HC and κLC paraproteins. The biclonality confirms the free HC occurs as a result of abnormal synthesis not cleavage. The clinical and immunological findings are clearly different to typical findings in both γ3HCD and Myeloma. HCD has an appalling prognosis and this case is likely to have been ‘smouldering’ for 18 months, evidenced by the 2 pneumonias and persistent night sweats. There is no lymphadenopathy or organomegaly associated with γ3HCD. The immunophenotype of the malignant plasma cells is unique. Other atypical features include frank proteinuria, with a HC in the urine, but normal renal function and no radiological or biochemical evidence of bone involvement. We propose that this unique biclonal myeloma has distinct immunological and clinical features.

Novel functions of clathrin light chains: clathrin heavy chain trimerization is defective in light chain-deficient yeast

1997 ◽  
Vol 110 (7) ◽  
pp. 899-910 ◽  
Author(s):  
K.M. Huang ◽  
L. Gullberg ◽  
K.K. Nelson ◽  
C.J. Stefan ◽  
K. Blumer ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
State Level ◽  
Light Chains ◽  
Chain Gene ◽  
Light Chain Gene ◽  
Heavy Chains ◽  
Clathrin Heavy Chain ◽  
Multicopy Suppressors ◽  
Delta Cells

Clathrin is a major coat protein involved in sorting and retention of proteins at the late Golgi and in endocytosis from the cell surface. The clathrin triskelion contains three heavy chains, which provide the structural backbone of the clathrin lattice and three light chains, which are thought to regulate the formation or disassembly of clathrin coats. To better understand the function of the clathrin light chain, we characterized yeast strains carrying a disruption of the clathrin light chain gene (CLC1). Light chain-deficient cells showed phenotypes similar to those displayed by yeast that have a disruption in the clathrin heavy chain gene (CHC1). In clc1-delta cells, the steady state level of the clathrin heavy chain was reduced to 20%-25% of wild-type levels and most of the heavy chain was not trimerized. If CHC1 was overexpressed in clc1-delta cells, heavy chain trimers were detected and several clc1-delta phenotypes were partially rescued. These results indicate that the light chain is important for heavy chain trimerization and the heavy chain still has some function in the absence of the light chain. In yeast, deletion of CHC1 is lethal in strains carrying the scd1-i allele, while strains carrying the scd1-v allele can survive without the heavy chain. In previous studies we isolated several multicopy suppressors of inviability of chc1-delta scd1-i cells. Surprisingly, one of these suppressors, SCD4, is identical to CLC1. Overexpression of CLC1 in viable chc1-delta scd1-v strains rescued some but not all of the phenotypes displayed by these cells. In the absence of the heavy chain, the light chain was not found in a high molecular mass complex, but still associated with membranes. These results suggest that the light chain can function independently of the clathrin heavy chain in yeast.

scholarly journals Thiol groups of normal immunoglobulin G

1974 ◽  
Vol 137 (2) ◽  
pp. 281-289 ◽  
Author(s):  
Barbara M. Buchwald ◽  
G. E. Connell
Keyword(s):  
Heavy Chain ◽  
Immunoglobulin G ◽  
Specific Radioactivity ◽  
Reduced Form ◽  
Light Chains ◽  
Thiol Groups ◽  
Myeloma Proteins ◽  
Disulphide Bonds ◽  
Sh Group ◽  
Normal Human

Normal human immunoglobulin G (IgG) was treated with radioactive N-ethylmaleimide in the absence of a reducing agent but in the presence of a denaturing solvent. The sites of reaction were determined by isolation of the radioactive peptides from thermolytic digests of the heavy and light chains. Six radioactive peptides were purified from the digest of the light chain and ten from that of the heavy chain. When sequenced, all the peptides were identical with peptides that would be predicted for the half-cystine residues involved in disulphide bonds. The specific radioactivity of the peptides indicated that the proportion of the half-cystine residues in the reduced form varied from 0.57 to 2.54%. These results indicate that the disulphide bonds of IgG are not completely oxidized. The estimate of 0.2mol of SH group/mol of IgG (Cecil & Stevenson, 1965; Luks & Connell, 1968) can be accounted for if 0.8% of every half-cystine residue of the intrachain bonds was in the reduced form. Variable cysteine residues as have been described in several myeloma proteins must occur extremely infrequently among the immunoglobulins.

Immunological phenotype of lymphomas induced by avian leukosis viruses

1983 ◽  
Vol 3 (6) ◽  
pp. 1077-1085
Author(s):  
L C Chen ◽  
S A Courtneidge ◽  
J M Bishop
Keyword(s):  
B Lymphocytes ◽  
Cell Lines ◽  
Light Chain ◽  
Avian Leukosis Virus ◽  
Immunoglobulin M ◽  
Light Chains ◽  
Free Light Chains ◽  
Viral Antigens ◽  
Immunological Phenotype ◽  
Avian Leukosis Viruses

The production of immunoglobulin by six cell lines derived from bursal tumors induced by avian leukosis virus follows two general patterns: (i) three cell lines that have been extensively passaged in culture synthesize and secrete light chains only; (ii) three cell lines that are recently isolated produce and secrete monomeric immunoglobulin M in addition to free light chains. All six cell lines synthesize and secrete both glycosylated and unglycosylated forms of light chain. We conclude that the cell lines established from lymphomas induced by avian leukosis virus represent relatively mature, but possibly abnormal, stages in the development of chicken B-lymphocytes. The immunoglobulin M produced by the cell lines failed to form detectable immune complexes with avian leukosis virus. It therefore appears that the immunoglobulin M is not directed against viral antigens and that autogenous antigenic stimulus cannot account for the sustained growth of the neoplastic B-lymphocytes.

scholarly journals Quantitative Immunoprecipitation Free Light Chain Mass Spectrometry (QIP-FLC-MS) Simplifies Monoclonal Protein Assessment and Provides Added Clinical Value in Systemic AL Amyloidosis

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4375-4375 ◽  
Author(s):  
Faye Amelia Sharpley ◽  
Hannah Victoria Giles ◽  
Richa Manwani ◽  
Shameem Mahmood ◽  
Sajitha Sachchithanantham ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Light Chain ◽  
Residual Disease ◽  
Renal Involvement ◽  
Light Chains ◽  
Al Amyloidosis ◽  
Free Light Chains ◽  
Accurate Identification ◽  
Monoclonal Protein ◽  
Serum And Urine

Introduction Early diagnosis, effective therapy and precise monitoring are central for improving clinical outcomes in systemic light chain (AL) amyloidosis. Diagnosis and disease response assessment is primarily based on the presence of monoclonal immunoglobulins and free light chains (FLC). The ideal goal of therapy associated with best outcomes is a complete responses (CR), defined by the absence of serological clonal markers. In both instances, detection of the monoclonal component (M-component) is based on serum FLC assessment together with traditional serum and urine electrophoretic approaches, which present inherent limitations and lack sensitivity particularly in AL where the levels are typically low. Novel mass spectrometry methods provide sensitive, accurate identification of the M-component and may prove instrumental in the timely management of patients with low-level amyloidogenic light chain production. Here we assess the performance of quantitative immunoprecipitation FLC mass spectrometry (QIP-FLC-MS) at diagnosis and during monitoring of AL amyloidosis patients treated with bortezomib-based regimens. Methods We included 46 serial patients with systemic AL amyloidosis diagnosed and treated at the UK National Amyloidosis Centre (UK-NAC). All patients had detailed baseline assessments of organ function and serum FLC measurements. Baseline, +6- and +12-month serum samples were retrospectively analysed by QIP-FLC-MS. Briefly, magnetic microparticles were covalently coated with modified polyclonal sheep antibodies monospecific for free kappa light chains (anti-free κ) and free lambda light chains (anti-free λ). The microparticles were incubated with patient sera, washed and treated with acetic acid (5% v/v) containing TCEP (20 mM) in order to elute FLC in monomeric form. Mass spectra were acquired on a MALDI-TOF-MS system (Bruker, GmbH). Results were compared to serum FLC measurements (Freelite®, The Binding Site Group Ltd), as well as electrophoretic assessment of serum and urine proteins (SPE, sIFE, UPE and uIFE). Results Cardiac (37(80%) patients) and renal (31(67%) patients) involvement were most common; 25(54%) patients presented with both. Other organs involved included liver (n=12), soft tissue (n=4), gastrointestinal tract (n=3) and peripheral nervous system (n=2). Baseline Freelite, SPE, sIFE and uIFE measurements identified a monoclonal protein in 42(91%), 22(48%), 34(74%) and 21(46%) patients, respectively. A panel consisting of Freelite + sIFE identified the M-component in 100% of the samples. QIP-FLC-MS alone also identified an M-component in 100% of the samples and was 100% concordant with Freelite for typing the monoclonal FLC (8 kappa, 34 lambda). In 4 patients, QIP-FLC-MS identified an additional M-protein that was not detected by the other techniques. In addition, 4/8(50%) kappa and 4/38(11%) lambda patients showed a glycosylation pattern of monoclonal FLCs at baseline by mass spectrometry. Interestingly, the frequency of renal involvement was significantly lower for patients with non-glycosylated forms (25% vs 76%, p=0.01), while no similar relationship was found for any other organs. During the 1-year follow-up period, 17 patients achieved a CR; QIP-FLC-MS identified serum residual disease in 13(76%) of these patients. Conclusion In our series, QIP-FLC-MS was concordant with current serum methods for identifying the amyloidogenic light chain type and provided, against all other individual tests, improved sensitivity for the detection of the monoclonal protein at diagnosis and during monitoring. The ability to measure the unique molecular mass of each monoclonal protein offers clone-specific tracking over time. Glycosylation of free light chains is over-represented in AL patients which may allow earlier diagnosis and better risk-assessment of organ involvement. Persistence of QIP-FLC-MS positive M component in patients otherwise in CR may allow targeted therapy. Overall, QIP-FLC-MS demonstrates potential to be exploited as a single serum test for precise serial assessment of monoclonal proteins in patients with AL amyloidosis. Disclosures Wechalekar: GSK: Honoraria; Janssen-Cilag: Honoraria; Amgen: Research Funding; Takeda: Honoraria; Celgene: Honoraria.

Lambda monoclonal free light chain abnormalities detected by a serum immunofixation electrophoresis assay are underrepresented by quantitative serum free light chain results

2021 ◽  
Vol 156 (Supplement_1) ◽  
pp. S13-S14
Author(s):  
Rebecca Treger ◽  
Kathleen Hutchinson ◽  
Andrew Bryan ◽  
Chihiro Morishima
Keyword(s):  
Light Chain ◽  
Free Light Chain ◽  
Light Chains ◽  
Sample Population ◽  
Free Light Chains ◽  
Serum Free ◽  
Serum Free Light Chain ◽  
Immunofixation Electrophoresis ◽  
High Concordance ◽  
Polyclonal Antisera

Abstract Protein and immunofixation (IFIX) electrophoresis are used to diagnose and monitor monoclonal gammopathies. While IFIX detects clonal production of intact immunoglobulins and free light chains (FLC), the latter can also be quantified using a serum free light chain (SFLC) assay, in which polyclonal antisera detects epitopes specific for free kappa (KFLC) or lambda light chains (LFLC). An abnormal KFLC: LFLC ratio (KLR) serves as a surrogate for clonality. While the SFLC assay is highly sensitive, normal LFLC (<2.63mg/dL) and KLR results (>0.26 & <1.65) were found in samples with distinct lambda monoclonal free light chains visualized by IFIX (X-LMFLC). To investigate this discordance, contemporaneous SFLC or KLR values were evaluated for their ability to accurately classify monoclonal FLCs identified by IFIX. We performed a retrospective analysis of serum and urine IFIX (Sebia Hydrasys) and SFLC (Freelite®, Binding Site) results from our institution between July 2010 through December 2020, using R 4.0.2 and Tidyverse packages. From among 9,594 encounters in which a single monoclonal component was initially identified by IFIX, 157 X-LMFLC and 131 X-KMFLC samples were analyzed. Elevated LFLC with normal KFLC was identified in 105/157 X-LMFLC samples (67%), while both LFLC and KFLC were elevated in 42/157 samples (27%). Concordance between X-KMFLC and KFLC was markedly higher, where 122/131 samples (93%) displayed elevated kappa FLC (>1.94mg/dL) with normal LFLC, and only 7/131 X-KMFLC samples (5%) possessed both elevated KFLC and LFLC. The use of KLR to identify pathogenic monoclonal free light chains improved lambda concordance to 85%; however, 19/157 (12%) of X-LMFLC samples still exhibited normal KLR. High concordance of 98% was again observed for X-KMFLC with abnormal KLR. When samples were segregated according to normal or impaired renal function (eGFR > or ≤60mL/min/1.73m², respectively), this disparate identification of X-LMFLC and X-KMFLC by the SFLC assay persisted, suggesting that renal dysfunction (as measured by eGFR) does not underlie this phenomenon. Lastly, we corroborated the above findings in a larger sample population by examining patients with urine Bence Jones FLC identified by IFIX who had free or intact monoclonal components in serum (N=724), grouped by lambda or kappa light chain involvement. The cause(s) of the discrepant performance by the Freelite® SFLC assay, relative to the Sebia Hydrasys IFIX assay, for identifying lambda FLC components is currently unclear. Possible contributory factors include assay reference range cutoffs, other patient disease parameters, and differences in assay-specific polyclonal antisera. Future analyses of these factors will help to further characterize SFLC assay performance and elucidate how interpretation of composite serum FLC test results can be improved to better guide patient management.

scholarly journals Differential reduction of interchain disulphide bonds of mouse immunoglobulin G

1968 ◽  
Vol 107 (6) ◽  
pp. 823-828 ◽  
Author(s):  
Alan R. Williamson ◽  
Brigitte A. Askonas
Keyword(s):  
Heavy Chain ◽  
Immunoglobulin G ◽  
Polyacrylamide Gel Electrophoresis ◽  
Partial Reduction ◽  
Free Light Chains ◽  
Myeloma Protein ◽  
Heavy Chains ◽  
Disulphide Bonds ◽  
Rabbit Immunoglobulin ◽  
Mouse Immunoglobulin

The relative lability of the interchain disulphide bonds of mouse G2a-myeloma protein 5563 was studied as a function of 2-mercaptoethanol concentration. Analysis of partial-reduction mixtures by polyacrylamide-gel electrophoresis and microdensitometry showed that the disulphide bonds between light and heavy chains are much more susceptible to reduction than the bonds between heavy chains. At a low concentration of 2-mercaptoethanol (10mm) the major dissociable products of mouse immunoglobulin G are heavy-chain dimers and free light chains. These findings contrast with the reported behaviour of rabbit immunoglobulin G, for which the lability of inter-heavy-chain bonds was found to exceed that of the bonds linking light and heavy chains (Hong & Nisonoff, 1965); the relative stability of rabbit immunoglobulin G interchain bonds was confirmed in the present study. Examination of human immunoglobulin G and an immunoglobulin G (γ2) of guinea pig showed that at least in the majority of molecules, as with mouse immunoglobulin G, the disulphide bonds between light and heavy chains are more susceptible to reduction than the inter-heavy-chain bonds.

scholarly journals In-house age-specific reference ranges for free light chains measured on the SPAPlus® analyser

2020 ◽  
Vol 57 (2) ◽  
pp. 138-143
Author(s):  
Lauren Campbell ◽  
Dawn Simpson ◽  
Adrian Shields ◽  
Berne Ferry ◽  
Karthik Ramasamy ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Light Chain ◽  
Filtration Rate ◽  
Estimated Glomerular Filtration Rate ◽  
Free Light Chain ◽  
Light Chains ◽  
Reference Ranges ◽  
Free Light Chains ◽  
Serum Free ◽  
Serum Free Light Chain

Background The measurement of monoclonal free light chains is being increasingly utilized since the introduction of serum-based assays. It is important for laboratories to determine their own reference ranges in order to reflect the local population. The aim of this study was to determine if age-adjusted reference ranges for serum free light chains would have implications for demand management of further laboratory investigations including immunofixation. Methods After certain exclusions, 4293 samples from individuals seen in primary care across Oxfordshire between 2014 and 2016 were identified for analysis of patient characteristics, serum free light chain results and estimated glomerular filtration rate. Results We found age to be an independent variable when considering serum free light chain concentrations, ratio and estimated glomerular filtration rate. The reference ranges derived from our data differ markedly from the original Binding Site ranges. When the age-specific ranges are retrospectively applied to our population, there is a 38% decrease in follow-up testing with no loss of specificity. Conclusion We feel confident implementing new age-specific serum free light chain reference ranges in our laboratory. We have developed a simple algorithm for evaluating serum free light chains based on age and estimated glomerular filtration rate. We encourage laboratories to establish their own local reference ranges using large cohorts and their chosen serum free light chain assay platform.

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