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.
- MeSH
- imunoblotting metody MeSH
- imunoelektroforéza metody MeSH
- isoelektrická fokusace * metody MeSH
- lehké řetězce imunoglobulinů * krev moč MeSH
- lidé středního věku MeSH
- lidé MeSH
- mnohočetný myelom moč krev MeSH
- paraproteinemie * moč diagnóza krev MeSH
- senioři MeSH
- senzitivita a specificita MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
In 1961, Svensson described isoelectric focusing (IEF), the separation of ampholytic compounds in a stationary, natural pH gradient that was formed by passing current through a sucrose density gradient-stabilized ampholyte mixture in a constant cross-section apparatus, free of mixing. Stable pH gradients were formed as the electrophoretic transport built up a series of isoelectric ampholyte zones-the concentration of which decreased with their distance from the electrodes-and a diffusive flux which balanced the generating electrophoretic flux. When polyacrylamide gel replaced the sucrose density gradient as the stabilizing medium, the spatial and temporal stability of Svensson's pH gradient became lost, igniting a search for the explanation and mitigation of the loss. Over time, through a series of insightful suggestions, the currently held notion emerged that in the modern IEF experiment-where the carrier ampholyte (CA) mixture is placed between the anolyte- and catholyte-containing large-volume electrode vessels (open-system IEF)-a two-stage process operates that comprises a rapid first phase during which a linear pH gradient develops, and a subsequent slow, second stage, during which the pH gradient decays as isotachophoretic processes move the extreme pI CAs into the electrode vessels. Here we trace the development of the two-stage IEF model using quotes from the original publications and point out critical results that the IEF community should have embraced but missed. This manuscript sets the foundation for the companion papers, Parts 2 and 3, in which an alternative model, transient bidirectional isotachophoresis is presented to describe the open-system IEF experiment.
The carrier ampholytes-based (CA-based) isoelectric focusing (IEF) experiment evolved from Svensson's closed system IEF (constant spatial current density, absence of convective mixing, counter-balancing electrophoretic and diffusive fluxes yielding a steady state pH gradient) to the contemporary open system IEF (absence of convective mixing, large cross-sectional area electrode vessels, lack of counter-balancing electrophoretic- and diffusive fluxes leading to transient pH gradients). Open system IEF currently is described by a two-stage model: In the first stage, a rapid IEF process forms the pH gradient which, in the second stage, is slowly degraded by isotachophoretic processes that move the most acidic and most basic CAs into the electrode vessels. An analysis of the effective mobilities and the effective mobility to conductivity ratios of the anolyte, catholyte, and the CAs indicates that in open system IEF experiments a single process, transient bidirectional isotachophoresis (tbdITP) operates from the moment current is turned on until it is turned off. In tbdITP, the anolyte and catholyte provide the leading ions and the pI 7 CA or the reactive boundary of the counter-migrating H3 O+ and OH- ions serves as the shared terminator. The outcome of the tbdITP process is determined by the ionic mobilities, pKa values, and loaded amounts of all ionic and ionizable components: It is constrained by both the transmitted amount of charge and the migration space available for the leading ions. tbdITP and the resulting pH gradient can never reach steady state with respect to the spatial coordinate of the separation channel.
In modern isoelectric focusing (IEF) systems, where (i) convective mixing is prevented by gels or small cross-sectional area separation channels, (ii) current densities vary spatially due to the presence of electrode vessels with much larger cross-sectional areas than those of the gels or separation channels, and (iii) electrophoretic and diffusive fluxes do not balance each other, stationary, steady-state pH gradients cannot form (open-system IEF). Open-system IEF is currently described as a two-stage process: A rapid IEF process forms the pH gradient from the carrier ampholytes (CAs) in the first stage, then isotachophoretic processes degrade the pH gradient in the second stage as the extreme pI CAs are moved into the electrode vessels where they become diluted. Based on the ratios of the local effective mobilities and the local conductivities ( μLeff(x)$\mu _{\rm{L}}^{{\rm{eff}}}( x )$ / κ(x)$\kappa ( x )$ values) of the anolyte, catholyte, and the CAs, we pointed out in the preceding paper (Vigh G, Gas B, Electrophoresis 2023, 44, 675-88) that in open-system IEF, a single process, transient, bidirectional isotachophoresis (tbdITP) operates from the moment current is turned on. In this paper, we demonstrate some of the operational features of the tbdITP model using the new ITP/IEF version of Simul 6.
We analyze the conditions of the adsorption of a flexible peptide onto a charged substrate in the 'wrong side' of the isoelectric point (WSIP), i.e. when surface and peptide charges have the same sign. As a model system, we focus on the casein macropeptide (CMP), both in the aglycosylated (aCMP) and fully glycosydated (gCMP) forms. We model the substrate as a uniformly charged plane while CMP is treated as a bead-and-spring model including electrostatic interactions, excluded volume effects and acid/base equilibria. Adsorption coverage, aminoacid charges and concentration profiles are computed by means of Monte Carlo simulations at fixed pH and salt concentration. We conclude that for different reasons the CMP can be adsorbed to both positively and negatively charged surfaces in the WSIP. For negatively charged surfaces, WSIP adsorption is due to the patchy distribution of charges: the peptide is attached to the surface by the positively charged end of the chain, while the repulsion of the surface for the negatively charged tail is screened by the small ions of the added salt. This effect increases with salt concentration. Conversely, a positively charged substrate induces strong charge regulation of the peptide: the acidic groups are deprotonated, and the peptide becomes negatively charged. This effect is stronger at low salt concentrations and it is more intense for gCMP than for aCMP, due to the presence of the additional sialic groups in gCMP.
- MeSH
- adsorpce MeSH
- cytidinmonofosfát MeSH
- izoelektrický bod MeSH
- kaseiny * MeSH
- peptidy * MeSH
- povrchové vlastnosti MeSH
- Publikační typ
- časopisecké články MeSH
Fourteen low molecular mass UV absorbing ampholytes containing 1 or 2 weakly acidic and 1 or 2 weakly basic functional groups that best satisfy Rilbe's requirement for being good carrier ampholytes (ΔpKa = pKamonoanion - pKamonocation < 2) were selected from a large group of commercially readily available ampholytes in a computational study using two software packages (ChemSketch and SPARC). Their electrophoretic mobilities were measured in 10 mM ionic strength BGEs covering the 2 < pH < 12 range. Using our Debye-Hückel and Onsager-Fuoss laws-based new software, AnglerFish (freeware, https://echmet.natur.cuni.cz/software/download), the effective mobilities were recalculated to zero ionic strength from which the thermodynamic pKa values and limiting ionic mobilities of the ampholytes were directly calculated by Henderson-Hasselbalch equation-type nonlinear regression. The tabulated thermodynamic pKa values and limiting ionic mobilities of these ampholytes (pI markers) facilitate both the overall and the narrow-segment characterization of the pH gradients obtained in IEF in order to mitigate the errors of analyte ampholyte pI assignments caused by the usual (but rarely proven) assumption of pH gradient linearity. These thermodynamic pKa and limiting mobility values also enable the reality-based numeric simulation of the IEF process using, for example, Simul (freeware, https://echmet.natur.cuni.cz/software/download).
Electrophoretic focusing on an inverse electromigration dispersion (EMD) profile is based on a principle different from those of other electrophoretic separation methods. It has already proved its applicability in analytical practice by offering competitive separation performance and sensitivity and specific selectivity. It can be classified as an intermediate between field-driven and equilibrium gradient methods and is therefore interesting from the viewpoint of theory of separation methods. This work presents a comprehensive theoretical description of electrophoretic focusing on an inverse EMD profile comprising properties of the electrolyte system, formed gradients, and focused analyte zones. The separation properties are described in terms of resolution and peak capacity and their dependence on system and analyte properties is discussed from the viewpoint of how the counteracting phenomena of electromigration and dispersion are affected by electric current, voltage, and hydrodynamic and electroosmotic flow. The overall performance of the present method is shown to be comparable with other electrophoretic separation methods like zone electrophoresis or isoelectric focusing.
Úvod: Nemoc těžkých řetězců gama je vzácné onemocnění dosud popsané přibližně u 150 případů. Cílem práce byla laboratorní diagnostika nemoci těžkých řetězců imunoglobulinu. Materiál a metody: Do FN Ostrava byl referován 60letý pacient pro suspektní lymfom marginální zóny z biopsie žaludku. U pacienta byla doplněna stagingová vyšetření vč. trepanobiopsie kostní dřeně a PET/CT. Ze speciálních vyšetření byla požadována elektroforéza sérových proteinů, imunofixační elektroforéza, stanovení polyklonálních imunoglobulinů, volných lehkých řetězců a párů těžkých/lehkých řetězců imunoglobulinů. Z důvodu nejasného nálezu byla doplněna izoelektrická fokusace v agarózovém gelu s následným afinitním imunoblottingem a SDS elektroforéza. Výsledky: V kostní dřeni bylo nalezeno 0,1 % plazmatických buněk, z toho 87 % klonálních (patologických) plazmocytů, s následujícím imunofenotypem: cyt LAMBDA+ CD38+ CD138+ CD45+ CD19+ CD56– CD27+ CD81– CD117–. V séru pacienta byly nalezeny monoklonální těžké řetězce gama. V moči monoklonální těžké ani lehké řetězce imunoglobulinu detekovány nebyly. PET/CT vyšetření prokázalo generalizovanou lymfadenopatii, splenomegalii a nehomogenní akumulaci fluorodeoxyglukózy v axilárním i apendikulárním skeletu, nicméně bez přítomnosti typických osteolytických ložisek. Závěr: Monoklonální těžké řetězce imunoglobulinů jsou vzácným onemocněním. Pro jejich potvrzení je nutné použít na rozdíl od průkazu kompletní molekuly paraproteinu další pomocné metody. Nález monoklonálního těžkého řetězce gama v séru studovaného pacienta souvisí s přítomností lymfomu marginální zóny, který byl prokázán z biopsie žaludku.
Background: Gamma-heavy chain disease is a rare disease, described so far in approximately 150 cases. The aim of this work was laboratory diagnostics of immunoglobulin heavy chain disease. Materials and methods: A 60-year-old patient was referred to the University Hospital in Ostrava for suspected marginal zone lymphoma from gastric biopsy. Staging examinations including bone marrow trepanobiopsy and PET/CT were added; special examinations required serum protein electrophoresis, immunofixation electrophoresis, determination of polyclonal immunoglobulins, free light chains, and immunoglobulin heavy/light chain pairs. Isoelectric focusing in agarose gel followed by affinity immunoblotting and SDS electrophoresis was added due to unclear findings. Results: 0.1 % of plasma cells were found in the bone marrow, of which 87 % were clonal (pathological) plasma cells, followed by the cyt cytotype LAMBDA + CD38 + CD138 + CD45 + CD19 + CD56- CD27 + CD81- CD117-. Monoclonal heavy chains were found in the patient‘s serum. No monoclonal immunoglobulin heavy or light chains were detected in urine. The PET/CT examination showed generalized lymphadenopathy, splenomegaly and inhomogeneous accumulation of fluorodeoxyglucose in axillary and appendicular skeleton, but without the presence of typical osteolytic lesions. Conclusion: Monoclonal heavy chains of immunoglobulins are a rare disease. In contrast to the detection of a complete paraprotein molecule, additional methods must be used to confirm them. The finding of monoclonal heavy chain gamma in the serum of the study patient is related to the presence of marginal zone lymphoma, which was proven from a gastric biopsy.
- MeSH
- elektroforéza v polyakrylamidovém gelu metody MeSH
- elektroforéza metody MeSH
- isoelektrická fokusace metody MeSH
- lidé středního věku MeSH
- lidé MeSH
- nemoc z těžkých řetězců * diagnóza patologie MeSH
- výsledek terapie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
The study aimed to investigate free light chain (FLC) monoclonality in patients with an abnormal free kappa/lambda ratio (FLC ratio). Seventy serum samples with abnormal FLC ratio were examined using an immunoturbidimetry (Binding Site, SPA) and the two different enzyme-linked immunosorbent assays (1. Sebia diagnostic kit; 2. in house methods), the monoclonal or oligoclonal bands of (FLC) by immunofixation electrophoresis (IE) and isoelectric focusing followed by affinity immunoblotting (IEF/AIB). The reference interval was calculated by non-parametric percentile method. 5.7% of samples examined by IE were suspected of monoclonal character of FLCs, but subsequently monoclonality was refuted by more sensitive IEF/AIB method; 7%, resp. 2.9% of samples showed FLC kappa, resp. FLC lambda oligoclonal character of bands. A statistically significant dependence was found between FLC ratio (Sebia) and FLC ratio (SPA), rs = 0.510, p = .001. Kappa statistic evaluated a fair conformity between the FLC ratio (Sebia) and IEF/AIB (kappa = 0.468) and between FLC ratio (in house) and IEF/AIB (kappa = 0.300). The verified reference interval for FLC ratio (Binding Site) is between 0.35 and 2.18. The IEF/AIB is the most sensitive method to discriminate between monoclonal and oligoclonal bands of FLC. The Binding Site and Sebia diagnostic kits do not give consistent results. The Binding Site diagnostic kit provides more results above reference interval of FLC ratios. For routine decision on monoclonality of the FLC ratio (SPA) it is advisable to use a verified reference interval.
- MeSH
- dospělí MeSH
- imunoglobuliny - lambda-řetězce analýza imunologie MeSH
- isoelektrická fokusace metody MeSH
- krevní proteiny analýza MeSH
- lidé středního věku MeSH
- lidé MeSH
- monoklonální protilátky analýza imunologie MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Cellulose-based preparative isoelectric focusing was used for preseparation and concentration of uropathogens Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Staphylococcus epidermidis, Candida albicans, and Candida parapsilosis in a urine sample containing a high concentration of human serum albumin. For the visibility of the colorless microbial zones in the separation medium, the microbial cells were labeled with red nonionogenic tenside (1-[[4-(phenylazo)phenyl]azo]-2-hydroxy-3-naphthoic acid polyethylene glycol ester, PAPAN). A very short incubation time, about 2 min, was sufficient for the adsorption of 0.001% (w/v) PAPAN onto the cell surface at the optimized conditions. As low as 103 cells of E. coli (pI 4.6) resuspended in 100 μL of urine sample and spiked with 0.1 mg mL-1 of human serum albumin (pI 4.8) were successfully preseparated and concentrated using this method. Because the pI values of the labeled microorganisms remained unchanged, the focused red zones of microbial cells were collected from the separation media and further analyzed by either capillary isoelectric focusing or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The viability of the cells extracted from the collected zones was also confirmed. The proposed method provides reliable, relatively fast, and cost-effective identification of uropathogens in urine specimens with a high level of albumin.
- MeSH
- Bacteria klasifikace izolace a purifikace MeSH
- barvení a značení metody MeSH
- houby klasifikace izolace a purifikace MeSH
- infekce močového ústrojí mikrobiologie MeSH
- isoelektrická fokusace MeSH
- lidé MeSH
- lidský sérový albumin analýza MeSH
- povrchově aktivní látky chemie MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
