28 research outputs found
Measurement of free light chains with assays based on monoclonal antibodies
Recently, serum free light chain (FLC) assays incorporating anti-kappa (魏) and anti-lambda (位) FLC monoclonal antibodies have become available: N Latex FLC assay (Siemens) and Seralite庐 (Abingdon Health). The purpose of this review is to provide an overview of these two new monoclonal antibody-based methods. In doing so, the review will outline the performance characteristics of each method, including a summary of: assay principles, antibody specificity, analytical performance and assay performance in disease. Additionally, the review will describe the potential user benefits of adopting these new generation FLC assays, which are designed to overcome the established limitations of existing polyclonal antibody based FLC assay
Prolongation of biologic dosing intervals in patients with stable psoriasis: a feasibility study
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N Latex FLC serum free light-chain assays in patients with renal impairment
The aim of this study was to establish ranges for N Latex free light-chain (FLC) monoclonal-based nephelometric assays in patients with renal impairment. In this retrospective study, serum samples from 284 patients with chronic kidney disease (CKD) stages 1-5 were measured with N Latex and Freelite FLC reagents on the Siemens BNII system and compared with controls without renal impairment. Both 魏FLC and 位FLC concentrations increased with the N Latex FLC and the Freelite assays with each increment in CKD stage. No difference was found in FLC 魏 concentrations between the two methods. In patients with renal failure, N Latex FLC detected higher concentrations of 位FLC (CKD5 median, 128 mg/L; 95% range, 43-302) compared with Freelite (89.5 mg/L, 35-197) (p <0.0001). This resulted in significantly different 魏/位 ratios in patients with CKD for the two tests. The Freelite 魏/位 ratio in the CKD5 group (median, 1.22; min-max, 0.22-2.70) was significantly increased compared with healthy controls (p <0.0001), and several individual samples were outside the reference range for healthy controls (0.26-1.65). In contrast, none of the 284 patients with CKD had an FLC 魏/位 ratio exceeding the N Latex reference limits for healthy controls (0.31-1.56). The N Latex FLC 魏/位 ratio in the CKD5 group (0.69, 0.32-1.54) was significantly lower compared with the control group (p <0.0001). These findings demonstrate that the N Latex FLC 魏/位 ratio in patients with renal failure did not differ from the reference limits for healthy control
Simultaneous Detection of 15 Human Cytokines in a Single Sample of Stimulated Peripheral Blood Mononuclear Cells
Cytokines secreted by cells of the immune system can alter the behavior and properties of immune or other cells. At a site of inflammation, sets of cytokines interact with immune cells, and their combined effect is often more important than the function of one isolated component. Conventional techniques, such as enzyme-linked immunosorbent assays, generally require large quantities of cells to characterize a complete cytokine profile of activated lymphocytes. The Bio-Plex system from Bio-Rad Laboratories combines the principle of a sandwich immunoassay with the Luminex fluorescent-bead-based technology. We developed a multiplex cytokine assay to detect different cytokines simultaneously in culture supernatant of human peripheral blood mononuclear cells stimulated with antigen and with mitogen. Fifteen human cytokines (interleukin 1伪 [IL-1伪], IL-1尾, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-15, IL-17, IL-18, gamma interferon, and tumor necrosis factor alpha) were validated with a panel of healthy individuals, rheumatoid arthritis patients, and juvenile idiopathic arthritis patients. Comparing the multiplex assay with a regular enzyme-linked immunosorbent assay technique with this donor panel resulted in correlation coefficients for all cytokines ranging from 0.75 to 0.99. Intra-assay variance proved to be less then 10%, whereas interassay variability ranged between 10 and 22%. This multiplex system proved to be a powerful tool in the quantitation of cytokines. It will provide a more complete picture in differences between activated lymphocyte cytokine profiles from healthy individuals and those from patients with chronic inflammatory diseases
Clinical comparison of new monoclonal antibody-based nephelometric assays for free light chain kappa and lambda to polyclonal antibody-based assays and immunofixation electrophoresis
Background: New monoclonal antibody-based assays for serum-free light chains (FLC) have become available. Methods: In a clinical study with 541 patients, the new N Latex FLC assays were compared with the Freelite (TM) FLC assays and immunofixation electrophoresis (IF). Results: Comparison of the different FLC kappa (kappa) assays showed a slope of 0.99 with a deviation of 5.0%, r(s)=0.92, for FLC lambda (lambda) a slope of 1.22, deviation 13.8%, r(s)=0.90 and for the kappa/lambda ratio a slope of 0.72, deviation -4.6%, r(s)=0.72. The concordance for the FLC kappa assays was 91%, for FLC lambda 85% and kappa/lambda ratio 95%. The clinical sensitivity and specificity of the kappa/lambda ratios in the study were comparable: 60% and 99% for the N Latex FLC assay and 61% and 97% for the Freelite (TM) assay. In IF-FLC positive samples, the N Latex FLC kappa/lambda ratio scored 20/23 (87%) samples outside the reference range and Freelite (TM) 21/23 (91%). For IF-FLC negative samples, N Latex FLC assay kappa/lambda ratio scored 338/350 (97%) within the reference range and Freelite (TM) scored 332/350 (95%). Conclusions: The concordance scores and the clinical sensitivity and specificity of the new N Latex FLC assays and Freelite (TM) assays appeared comparable, but there are some differences in measurement of concentrations between the method
Prolongation of biologic dosing intervals in patients with stable psoriasis: a feasibility study
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Prolongation of biologic dosing intervals in patients with stable psoriasis: a feasibility study
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Nucleosome-releasing factor: a new role for factor VII-activating protease (FSAP)
Plasma proteins such as early complement components and IgM are involved in the removal of late apoptotic or secondary necrotic (sn) cells. We have recently described how a plasma protease that could be inhibited by the protease inhibitor aprotinin was essential to remove nucleosomes from sn cells. An obvious candidate, plasmin, did indeed have nucleosome-releasing factor (NRF) activity. However, recalcified plasma (r-plasma) retained its NRF activity after plasminogen depletion, which suggests the existence of another protease responsible for NRF activity in plasma. In this study we have used size-exclusion and anion-exchange chromatography to purify the protease responsible for NRF activity in plasma. SDS-PAGE analysis of chromatography fractions containing NRF activity revealed a protein band corresponding with NRF activity. Sequence analysis showed this band to be factor VII-activating protease (FSAP). We developed monoclonal antibodies to FSAP and were able to completely inhibit NRF activity in plasma with monoclonal antibodies to FSAP. Using affinity chromatography we were able to purify single-chain (sc) FSAP from r-plasma. Purified scFSAP efficiently removes nucleosomes from sn cells. We report that factor VII-activating protease may function in cellular homeostasis by catalyzing the release of nucleosomes from secondary necrotic cell