Anti C-reactive Protein Research Articles

A Review of Anti-C Reactive Protein Antibodies in Systemic Lupus Erythematosus

Abstract Systemic lupus erythematosus (SLE), the prototype autoimmune disease, is characterized by the production of a plethora of autoantibodies with various roles in the development of disease-related tissue damage. C-reactive protein (CRP) is an acute phase reactant with a pentameric structure. Under acidic or alkaline conditions, or when urea levels are high and/or calcium levels are low, the pentamer (pCRP) dissociates irreversibly into monomeric CRP (mCRP) and exposes new epitopes (neo-CRP). Importantly, anti-mCRP (but not anti-pCRP) antibodies have been described in patients with SLE, their prevalence varying from 4% to 78% in different cohorts. Numerous studies have investigated the relationship between autoantibodies directed against CRP (anti-CRP) and disease activity as well as their association with lupus nephritis (LN), frequently reporting discrepant findings. The main objective of the present review is to describe the role of anti-mCRP antibodies in SLE according to the currently available data.

Synergistic Use of Gold Nanoparticles (AuNPs) and "Capillary Enzyme-Linked Immunosorbent Assay (ELISA)" for High Sensitivity and Fast Assays.

Using gold nanoparticles (AuNPs) on “capillary enzyme-linked immunosorbent assay (ELISA)”, we produced highly sensitive and rapid assays, which are the major attributes for point-of-care applications. First, in order to understand the size effect of AuNPs, AuNPs of varying diameters (5 nm, 10 nm, 15 nm, 20 nm, 30 nm, and 50 nm) conjugated with Horseradish Peroxidase (HRP)-labeled anti-C reactive protein (antiCRP) (AuNP•antiCRP-HRP) were used for well-plate ELISA. AuNP of 10 nm produced the largest optical density, enabling detection of 0.1 ng/mL of CRP with only 30 s of incubation, in contrast to 10 ng/mL for the ELISA run in the absence of AuNP. Then, AuNP of 10 nm conjugated with antiCRP-HRP (AuNP•antiCRP-HRP) was used for “capillary ELISA” to detect as low as 0.1 ng/mL of CRP. Also, kinetic study on both 96-well plates and in a capillary tube using antiCRP-HRP or AuNP•antiCRP-HRP showed a synergistic effect between AuNP and the capillary system, in which the fastest assay was observed from the “AuNP capillary ELISA”, with its maximum absorbance reaching 2.5 min, while the slowest was the typical well-plate ELISA with its maximum absorbance reaching in 13.5 min.

Immunosensors for C-Reactive Protein Based on Ultrathin Films of Carboxylated Cellulose Nanofibrils.

C-reactive protein (CRP) is an acute phase protein that has been widely used as a predictor of cardiovascular diseases. We report herein the synthesis of immunosensors based on carboxylated cellulose nanofibrils (CNF) for CRP detection, as demonstrated by quartz crystal microgravimetry (QCM). QCM sensors carrying ultrathin films of carboxylated CNF were prepared by using two protocols: (i) spin coating of CNF on the sensors followed by carboxylation via in situ oxidation with 2,2,6,6-tetramethylpiperidine 1-oxyl and (ii) carboxymethylation of CNF in aqueous dispersion followed by spin coating deposition on the sensors. Protein A was conjugated to the carboxylated CNF via N-(3-(Dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide and used as a ligand for oriented immobilization of anti C-reactive protein (anti-CRP). The different carboxyl group density of the two oxidized CNF surfaces influenced Protein A binding and, subsequently, the available immobilized anti-CRP molecules. The detection efficiency for CRP, specificity, and concentration range displayed by the carboxylated CNF-based immunosensors coupled with oriented and unoriented anti-CRP were determined and compared.

Inkjet monitoring technique with quartz crystal microbalance (QCM) sensor for highly reproducible antibody immobilization

We demonstrate that a calibrated amount of a biomolecule can be microdeposited using a commercially available quartz crystal microbalance (QCM) and a piezoelectric inkjet head with a flattened surface surrounding the ejection hole. Covering the QCM with a stainless-steel cover perforated with a precisely-machined hole both significantly decreased background noise due to external sources such as air flow and temperature fluctuations and allowed accurate droplet ejection at a constant temperature. Anti-c reactive protein antibody solution (anti-CRP; 1.0mg/ml) was continuously ejected onto a microchannel target using a piezoelectric injector; its microdeposition was monitored shot-by-shot using a 30MHz QCM. The dispersion of the QCM frequency change per shot decreased from 7.87 to 1.01Hz when a perforated stainless-steel cover was installed. The primary antibody was precisely deposited on the target with high reproducibility. The variation in luminescence measured by enzyme-linked immunosorbant assay (ELISA) decreased from 9.67% to 1.16% when calibrating the amount of primary antibody deposition with this developed technique.

Anti-C reactive protein antibodies in Indian patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by over production of autoantibodies. C-reactive protein (CRP) is a phylogenetically highly conserved plasma protein that participates in the systemic response to inflammation. Anti-CRP antibodies might have biological functions of pathogenetic interest in SLE. We evaluated anti-CRP antibodies in Indian SLE patients and their association with anti-dsDNA antibodies and complement levels (C3 and C4). One hundred SLE patients diagnosed according to the American College of Rheumatology criteria were included. Disease activity was assessed using SLE disease activity index (SLEDAI). Anti-CRP autoantibodies were detected by enzyme linked immunosorbent assay. Anti-dsDNA antibodies were detected by indirect immunofluroscence test (Euroimmun Lubeck, Germany). High sensitivity CRP and complement levels (C3, C4) were detected using a Nephelometer. (BN ProSpec, Dade Behring, Germany). Anti-CRP antibodies were detected in 26% of SLE patients. Mean age of disease onset among anti-CRP positives was 22.4 ± 7.5, and 26.6 ± 9.3 years among anti-CRP negatives (P > 0.05). Anti-dsDNA positivity was significantly higher among anti-CRP positives (32.7%) as compared to anti-CRP negatives (16%) (P = 0.00519). No statistically significant difference was observed in SLEDAI scores of anti-CRP positive group and anti-CRP negative group (P > 0.05). We observed a positive correlation between anti-CRP antibodies and anti-dsDNA antibodies.

Nephritogenic-antinephritogenic antibody network in lupus glomerulonephritis

Lupus glomerulonephritis (LGN) is one of the most threatening manifestations of systemic lupus erythematosus (SLE) and a major predictor of poor prognosis. The mechanisms leading to kidney inflammation are not completely clear; however, autoantibodies seem to play a pivotal role. Apoptosis dysregulation in SLE is likely to trigger generation of autoantibodies, the released nucleosomes being the driving autoantigen for further epitope amplification and selection of DNA or nucleosome-specific B cells. Growing evidence supports a multistep path to LGN involving initial autoantibody binding to chromatin fragments in the mesangial matrix, where they can induce mesangial inflammation leading to a shut-down of the renal DNase gene, generation and deposition of secondary necrotic chromatin on the glomerular basement membrane favouring antibody binding, complement activation and development of membrano-proliferative glomerular lesions. Anti-DNA IgG antibodies display the major pathogenetic potential in LGN initiation; however, other isotypes (IgA or IgE) as well as autoantibodies targeting other molecules (e.g. anti-C1q, anti-C reactive protein) can perpetuate renal injury. Conversely, protective autoantibodies are also likely in SLE which can contain renal damage targeting either DNA (i.e. IgM anti-DNA) or other molecules (e.g. pentraxin 3). Thus, lupus nephritogenic-antinephritogenic antibodies orchestrate the balance between harm and defence of renal tissue.

Antibody Clustering Helps Refine Lupus Prognosis

Our aim was to investigate a possible association between patterns of anti-dsDNA antibody isotypes (IgG, IgM, and IgA), rheumatoid factor (RF) isotypes (IgG, IgM, IgA), and IgG anti-C reactive protein (CRP) and systemic lupus erythematosus (SLE) disease activity (SLEDAI). Our study group included 98 patients, 86 women and 12 men, with a mean SLEDAI score of 7.9 +/- 4.1. We divided the patients into 4 groups by the serum anti-dsDNA antibody isotype intensity level. We found that patients in group 1 (IgG > IgM, 42 patients) had a statistically significantly higher SLEDAI score than group 2 (IgG < IgM, 13 patients) (10.57 +/- 4.62 versus 5.6 +/- 4, P = 0.0012), group 3 (IgG = IgM, 8 patients) (10.57 +/- 4.62 versus 6.2 +/- 1.98, P = 0.04), and group 4 (none, 35 patients) (10.57 +/- 4.62 versus 6 +/- 1.5, P = 0.0001). SLE patients with IgG RF or IgM RF isotype present had a significantly higher SLEDAI score compared with those without IgG RF or IgM RF (10.57 +/- 4.8 versus 7.6 +/- 4.1, P = 0.03, 10.6 +/- 5 versus 7.6 +/- 3.9, P = 0.046). The presence of IgA RF isotype was not associated with a higher SLEDAI score. IgG anti-CRP did not correlate differentially with SLEDAI scores. A combination of high-titer IgG anti-dsDNA with a positive RF of IgM isotype may serve as a marker for more active SLE.

Anti C-Reactive Protein Immobilization Onto Poly(glycidyl Methacrylate) Microspheres and its Use for Diagnosis

A method for a polymeric carrier based test was developed for the diagnosis of C-reactive protein (CRP) as an alternative to commercial kits. Poly(glycidyl methacrylate) (PGMA) particles were synthesized by dispersion polymerization method from the glycidyl methacrylate (GMA) monomer. The monomer transformation value was 88.67% by weight. In the first step the epoxide rings were opened to form amine groups on the particle surfaces. The optimized conditions were found for the antigen to be immobilized onto the surface-modified microspheres. Agglutination tests were carried out under in vitro conditions with the anti-human CRP immobilized microspheres with samples from patient serum. Relatively high sensitivity was obtained with a short reaction time between doing the test after receiving patient serum compared with the selected commercial kit now in use. By referring to the agglutination intensity scores, using only 10 mg/L samples of plasma, the CRP concentration was detectable with these new kits.

Monodispersed polystyrene latex particles functionalized by the macromonomer technique. II. Application in immunodiagnosis

AbstractMonodispersed polymer colloids with aldehyde and acetal functionalities, introduced by the macromonomer technique, were synthesized by a two‐step emulsion polymerization process. The latex samples so formed were chosen as the polymeric support to carry out covalent coupling with the antibody IgG anti‐C reactive protein, to test the utility of the latex–protein complexes formed in immunoassays. More than the 45% of the initially linked protein was covalently coupled in the acetal latex samples. Copyright © 2001 John Wiley &amp; Sons, Ltd.

Acetal-functionalized polymer particles useful for immunoassays. III: preparation of latex-protein complexes and their applications.

Monodisperse polymer colloids with dimethyl and diethyl acetal functionalities synthesized by a two-step emulsion polymerization process were chosen as the polymeric support to carry out covalent coupling with the antibody IgG anti C-reactive protein, and to test the utility of the latex-protein complexes formed in immunoassays with the specific CRP antigen. More than the 80% of the initially linked protein was covalently coupled in all of the latexes. The agglutination reaction was followed by turbidimetry. With the aim of analyzing the effect of some of the variables of the immunological reaction, the reaction time, the particle concentration and the coverage degree of protein in the complexes were varied.

Synthesis and characterization of cationic latex particles bearing sulfhydryl groups and their use in the immobilization of Fab antibody fragments (1)

Emulsion copolymerization of styrene and a cationic monomer vinylbenzyl-isothiouronium chloride (VBIC) with initiation by 2,2′ azobis(2-amidinopropane)-dihydrochloride (V-50) gave monodisperse latex particles. After post-stabilization with cationic or non-ionic surfactants, the colloids were diluted in basic buffers with concomitant deprotection of the sulfhydryl groups. Therefore, coupling reactions on the latex beads were possible. Coupling conditions were determined with Ellman's reagent.14C iodoacetamide and anti C-reactive protein antibody Fab fragments were immobilized and finally, the immunological activity of the sensitized latex was assessed.

Selection and performance of monoclonal anti-C-reactive protein in ELISA quantitative assay

Nine monoclonal anti C-reactive protein (CRP) antibodies were tested as peroxidase-conjugates in a CRP binding to a solid-phase phosphorylethanolamine (PE) assay. One monoclonal antibody was selected due to its high yield of conjugate, titre and stability. The use of monoclonal antibodies increased assay sensitivity, precision and allowed assay simplification by the simultaneous rather than sequential incubation of CRP and conjugate. Comparison with nephelometry and CRP binding to PE assay using polyclonals gave correlations ⩾ 0.9. By using monoclonal conjugates to assay human sera, healthy adult CRP levels were found to be lower than by using polyclonal conjugates. Samples with very low CRP contents might now be assayed with higher precision.

A Latex Agglutination Test for Measuring Antibodies to Streptococcal Mucopeptides

Abstract The preparation and application of mucopeptide (MP)-coated latex particles for determining antibody to streptococcal group A MP is described. Anti-MP hyperimmune sera, normal animal and human sera, and commercial antisera to various antigens were tested. MP-latex agglutination proved to be both specific and highly sensitive, permitting the detection of low antibody levels in 20 to 40% of normal sera; these antibodies were not demonstrable by means of other serologic techniques. Data confirming the specificity of the reaction are presented. No cross-agglutinations were observed with the exception of commercial anti-C reactive protein (CRP) serum. This latter phenomenon may be due to traces of MP present in the preparations used to produce anti-CRP serum. Latex agglutination should prove useful for establishing the occurrence of anti-MP antibody and for elucidating the role of anti-MP antibody in the various toxic or inflammatory reactions induced by MP in vitro and in vivo.