Immunoaffinity based methods are superior to kits for purification of prostate derived extracellular vesicles from plasma samples

BACKGROUND

The ability to isolate extracellular vesicles (EVs) such as exosomes or microparticles is an important method that is currently not standardized. While commercially available kits offer purification of EVs from biofluids, such purified EV samples will also contain non-EV entities such as soluble protein and nucleic acids that could confound subsequent experimentation. Ideally, only EVs would be isolated and no soluble protein would be present in the final EV preparation.

METHODS

We compared commercially available EV isolation kits with immunoaffinity purification techniques and evaluated our final EV preparations using atomic force microscopy (AFM) and nanoscale flow cytometry (NFC). AFM is the only modality capable of detecting distinguishing soluble protein from EVs which is important for downstream proteomics approaches. NFC is the only technique capable of quantitating the proportion of target EVs to non-target EVs in the final EV preparation.

RESULTS

To determine enrichment of prostate derived EVs relative to non-target MPs, anti-PSMA (Prostate Specific Membrane Antigen) antibodies were used in NFC. Antibody-based immunoaffinity purification generated the highest quality of prostate derived EV preparations due to the lack of protein and RNA present in the samples. All kits produced poor purity EV preparations that failed to deplete the sample of plasma protein.

CONCLUSIONS

While attractive due to their ease of use, EV purification kits do not provide substantial improvements in isolation of EVs from biofluids such as plasma. Immunoaffinity approaches are more efficient and economical and will also eliminate a significant portion of plasma proteins which is necessary for downstream approaches.

Extracorporeal IgE Immunoadsorption in Allergic Asthma: Safety and Efficacy

BACKGROUND

Prevention of IgE-binding to cellular IgE-receptors by anti-IgE (Omalizumab) is clinically effective in allergic asthma, but limited by IgE threshold-levels. To overcome this limitation, we developed a single-use IgE immunoadsorber column (IgEnio). IgEnio is based on a recombinant, IgE-specific antibody fragment and can be used for the specific extracorporeal desorption of IgE.

OBJECTIVE

To study safety and efficacy of IgEnio regarding the selective depletion of IgE in a randomized, open-label, controlled pilot trial in patients with allergic asthma and to investigate if IgEnio can bind IgE-Omalizumab immune complexes.

METHODS

Fifteen subjects were enrolled and randomly assigned to the treatment group (n=10) or to the control group (n=5). Immunoadsorption was done by veno-venous approach, processing the twofold calculated plasma volume during each treatment. A minimum average IgE-depletion of 50% after the last cycle in the intention-to-treat population was defined as primary endpoint. Safety of the treatment was studied as secondary endpoint. In addition, possible changes in allergen-specific sensitivity were investigated, as well as clinical effects by peak flow measurement and symptom-recording. The depletion of IgE-Omalizumab immune complexes was studied in vitro. The study was registered at clinicaltrials.gov (NCT02096237) and conducted from December 2013 to July 2014.

RESULTS

IgE immunoadsorption with IgEnio selectively depleted 86.2% (±5.1% SD) of IgE until the end of the last cycle (p<0.0001). Removal of pollen allergen-specific IgE was associated with a reduction of allergen-specific basophil-sensitivity and prevented increases of allergen-specific skin-sensitivity and clinical symptoms during pollen seasons. IgEnio also depleted IgE-Omalizumab immune complexes in vitro. The therapy under investigation was safe and well-tolerated. During a total of 81 aphereses, 2 severe adverse events (SAE) were recorded, one of which, an episode of acute dyspnea, possibly was related to the treatment and resolved after administration of antihistamines and corticosteroids.

CONCLUSIONS

This pilot study indicates that IgE immunoadsorption with IgEnio may be used to treat patients with pollen-induced allergic asthma. Furthermore, the treatment could render allergic patients with highly elevated IgE-levels eligible for the administration of Omalizumab and facilitate the desorption of IgE-Omalizumab complexes. This study was funded by Fresenius Medical Care Deutschland GmbH, Bad Homburg, Germany.

Integrated acoustic immunoaffinity-capture (IAI) platform for detection of PSA from whole blood samples

On-chip detection of low abundant protein biomarkers is of interest to enable point-of-care diagnostics. Using a simple form of integration, we have realized an integrated microfluidic platform for the detection of prostate specific antigen (PSA), directly in anti-coagulated whole blood. We combine acoustophoresis-based separation of plasma from undiluted whole blood with a miniaturized immunoassay system in a polymer manifold, demonstrating improved assay speed on our Integrated Acoustic Immunoaffinity-capture (IAI) platform. The IAI platform separates plasma from undiluted whole blood by means of acoustophoresis and provides cell free plasma of clinical quality at a rate of 10 uL/min for an online immunoaffinity-capture of PSA on a porous silicon antibody microarray. The whole blood input (hematocrit 38-40%) rate was 50 μl min(-1) giving a plasma volume fraction yield of ≈33%. PSA was immunoaffinity-captured directly from spiked female whole blood samples at clinically significant levels of 1.7-100 ng ml(-1) within 15 min and was subsequently detected via fluorescence readout, showing a linear response over the entire range with a coefficient of variation of 13%.

[Research of on-line vision inspection technology for width of NC membrane]

This paper presents a vision-based method for the width of NC membrane online inspection. In the production of bio-test strip, the number of antigen or antibody which is coated on the membrane depends on the width and the uniformity of test line T and control line C. People should control the width and the uniformity strictly to ensure the accuracy of lines in order to achieve quantitative inspection with high sensitivity. And online inspection must be done, it cannot be processed when the solution has been dry up. This paper gives a design of online inspection system based on linear charge-coupled device (linear CCD), it makes such advantages in terms of speed, accuracy, and the operation to achieve real-time, online inspection.

Performance of an automated solid-phase red cell adherence system compared with that of a manual gel microcolumn assay for the identification of antibodies eluted from red blood cells

IgG antibodies coating red blood cells (RBCs) can be removed by elution procedures and their specificity determined by antibody identification studies. Although such testing is traditionally performed using the tube agglutination assay, prior studies have shown that the gel microcolumn (GMC) assay may also be used with comparable results. The purpose of this study was to compare an automated solid-phase red cell adherence (SPRCA) system with a GMC assay for the detection of antibodies eluted from RBCs. Acid eluates from 51 peripheral blood (PB) and 7 cord blood (CB) samples were evaluated by both an automated SPRCA instrument and a manual GMC assay. The concordance rate between the two systems for peripheral RBC samples was 88.2 percent (45 of 51), including cases with alloantibodies (n = 8), warm autoantibodies (n = 12), antibodies with no identifiable specificity (n = 2), and negative results (n = 23). There were six discordant cases, of which four had alloantibodies (including anti-Jka, -E, and -e) demonstrable by the SPRCA system only. In the remaining 2 cases, anti-Fya and antibodies with no identifiable specificity were demonstrable by the GMC assay only. All seven CB specimens produced concordant results, showing anti-A (n = 3), -B (n = 1), maternal anti-Jka (n = 2), or a negative result (n = 1). Automated SPRCA technology has a performance that is comparable with that of a manual GMC assay for identifying antibodies eluted from PB and CB RBCs.

[Lanthanide fluorescence immunoassay of 17alpha-hydroxyprogesterone in dried blood samples for neonatal screening for adrenogenital syndrome]

The first Russian assay of 17alpha-hydroxyprogesterone in dried blood spots has been developed to use for neonatal screening for adrenogenital syndrome (AGS). The technique is modeled on solid-phase lanthanide fluorescence immunoassay with time-resolution detection and it ensures the hormone to be determined in a 3.2-mm dried blood spot in the concentration range of 0 to 400 nmol/l, the coefficient of variation being not greater than 15%, and the results correlated with those of the DELFIA Neo170HP test system. The tests of 387 dried blood samples carried out in three regions have demonstrated the efficiency of the technique for screening and verifying neonatal AGS.

Microfluidic, bead-based assay: Theory and experiments

Microbeads are frequently used as a solid support for biomolecules such as proteins and nucleic acids in heterogeneous microfluidic assays. However, relatively few studies investigate the binding kinetics on modified bead surfaces in a microfluidics context. In this study, a customized hot embossing technique is used to stamp microwells in a thin plastic substrate where streptavidin-coated agarose beads are selectively placed and subsequently immobilized within a conduit. Biotinylated quantum dots are used as a label to monitor target analyte binding to the bead's surface. Three-dimensional finite element simulations are carried out to model the binding kinetics on the bead's surface. The model accounts for surface exclusion effects resulting from a single quantum dot occluding multiple receptor sites. The theoretical predictions are compared and favorably agree with experimental observations. The theoretical simulations provide a useful tool to predict how varying parameters affect microbead reaction kinetics and sensor performance. This study enhances our understanding of bead-based microfluidic assays and provides a design tool for developers of point-of-care, lab-on-chip devices for medical diagnosis, food and water quality inspection, and environmental monitoring.

Variability of anti-PF4/heparin antibody results obtained by the rapid testing system ID-H/PF4-PaGIA

BACKGROUND

Recent studies have shown that a low clinical pretest probability may be adequate for excluding heparin-induced thrombocytopenia. However, for patients with intermediate or high pretest probability, laboratory testing is essential for confirming or refuting the diagnosis. Rapid assessment of anti-PF4/heparin-antibodies may assist clinical decision-making.

OBJECTIVES

To evaluate the performance of rapid ID-H/PF4-PaGIA. In particular, we verified reproducibility of results between plasma and serum specimens, between fresh and frozen samples, and between different ID-H/PF4-polymer lots (polystyrene beads coated with heparin/PF4-complexes).

PATIENTS/METHODS

The samples studied were 1376 plasma and 914 corresponding serum samples from patients investigated for suspected heparin-induced thrombocytopenia between January 2000 and October 2008. Anti-PF4/heparin-antibodies were assessed by ID-H/PF4-PaGIA, commercially available ELISAs and heparin-induced platelet aggregation test.

RESULTS

Among 914 paired plasma/serum samples we noted discordant results (negative vs. low-titre positive) in nine instances (1%; 95%CI, 0.4-1.6%). Overall, agreement between titres assessed in plasma vs. serum was highly significant (Spearman correlation coefficient, 0.975; P < 0.0001). Forty-seven samples tested both fresh and after freezing/thawing showed a good agreement, with one discordant positive/negative result (Spearman correlation coefficient, 0.970; P < 0.0001). Among 1376 plasma samples we noted a strikingly variable incidence of false negative results (none - 82%; 95%CI, 66-98%), depending on the employed ID-H/PF4-polymer lot. Faulty lots can be recognized by titrating commercial positive controls and stored samples of HIT-patients.

CONCLUSION

Laboratories performing the assay should implement stringent internal quality controls in order to recognize potentially faulty ID-H/PF4-polymer lots, thus avoiding false negative results.

New Ligand Coupling Procedure for Formation of an Immunoadsorption Wall

To prevent the occurrence of dialysis-related amyloidosis, an immunoadsorption wall based on polyacrylamide has been manufactured by a recently developed, partially incomplete, two-stage polymerization method. During the preparation process, efficient utilization of coupling antibodies is the key to large-scale production of such a toxin removal modality. In this study, we attempted to carry out the ligand coupling procedure after formation of a cyanogen bromide (CNBr)-activated stationary phase, using anti-beta2-microglobulin (beta-2M) antibodies. In vitro immunoadsorption tests show that the levels of beta-2M decrease rapidly within the first 2 hours for all the immunoadsorption tests. After that, nearly blank values were reached for tests of initial levels of c. 30 microg/mL and c. 82 microg/mL, whereas a relatively constant level of c. 10 microg/mL was maintained for the test of initial levels of c. 185 microg/mL. The maximum surface binding capacity of the prepared immunoadsorption walls is estimated by fitting experimental data, using a mathematical model of saturation kinetics. The present comparative investigation also suggests the manufacturing process for an immunoadsorption wall could be improved and facilitated by this new ligand coupling procedure without compromising the resulting binding capacity. Furthermore, the experimental protocols as well as the present methodology could be helpful for development of a clinically applicable immunoadsorption wall.

Immunoadsorption with single-use columns for the management of bleeding in acquired hemophilia A: A series of nine cases

BACKGROUND

Acquired hemophilia A in a setting of bleeding or required surgery frequently places patients into a state of critical illness with high mortality. In this context immunoadsorption (IA) can be used to eliminate coagulation inhibitors quickly to employ recombinant coagulation factors more effectively. However, since acquired hemophilia is a rare condition the therapy is little standardized.

METHODS

We report on a retrospective analysis of nine cases of acquired hemophilia A treated with IA using disposable adsorber columns. Data collection was performed by retrospectively reviewing the patients' files regarding clinical course, mode of therapy, inhibitor titers, and coagulation status.

RESULTS

Inhibitor titers were effectively reduced in all but one patient following the treatment with IA. In two out of seven patients surviving the acute bleeding an inhibitor relapse occurred. The overall remission rate was determined as 77.8% within a median follow-up of 613 days. In two of our nine patients fatal outcome resulted due to major bleeding complications. IA treatment showed good tolerability and no fatal complications were caused.

CONCLUSION

The presented cases support our assumption that patients with acquired hemophilia A benefit from IA with disposable columns in a setting of acute bleeding. This modality of IA is able to eliminate inhibitors reliably and quickly. IA in general is substantially speeding up the progress of therapy preventing bleeding complications constantly threatening the patient and reducing the dosages of coagulation factor therapy. We encourage IA with disposable columns in all bleeding patients with acquired hemophilia to aggressively lower the inhibitors.

Treatment of chronic dilated cardiomyopathy with immunoadsorption using the staphylococcal A-Agarose column: A comparison of immunoglobulin reduction using two different techniques

Auto-antibodies to myocardial antigens have been implicated in the pathogenesis of chronic dilated cardiomyopathy (DCM). A protein A immunoadsorption affinity column system was used to remove IgG antibodies, particularly IgG3. Two techniques, the standard technique (T-1) used for removal of IgG Factor VIII inhibitors and a technique (T-2) designed to enhance IgG3 removal and address issues in venous access, minimize positive fluid balance, and adverse reactions were compared. A total of four patients were treated, two patients were treated for 5 consecutive days with each technique. T-2 resulted in larger, but not significantly so, IgG3 reduction (70% and 63%) than T-1 (53% and 59%). Both techniques lowered total IgG levels by >or=93%. Because of venous access problems, 60% of T-1 procedures reached the plasma volume target versus 100% for T-2. Positive fluid balance was significantly lower for T-2 (+507 +/- 465) ml versus T-1 (+2,206 +/- 724) ml. Overall adverse event (AE) rate (T-1:16, T-2:15) was similar between the techniques but demonstrated a statistically significant difference in the types of reactions that occurred. All AE were mild in nature, common to other apheresis procedures, and were easily managed. This small study, demonstrated that a modified technique (T-2) with superior fluid balance should be used when treating DCM with the Immunosorba system.

A pilot study to assess the use of protein a immunoadsorption for chronic dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a leading cause of end-stage heart failure and cardiac transplantation. Anticardiac antibodies are common and removal of these through immunoadsorption (IA) is associated with improvement in global cardiac function. The effect of IA on regional function and quality of life (QOL) without intravenous immunoglobulin (IVIG) substitution has not been described. We performed a pilot trial using Immunosorba columns in four patients with chronic DCM and NYHA Class II-III congestive heart failure. Subjects were followed for 6 months with serial echocardiograms and validated QOL assessments. Regional and global left ventricular (LV) end-systolic deformations were assessed by two-dimensional strain echocardiography. Total IgG decreased 95% (from 1,210 +/- 274 mg/dl to 57 +/- 16 mg/dl, P = 0.003) and IgG3 decreased 61% (from 33 +/- 16 mg/dl to 13 +/- 7 mg/dl, P = 0.024). QOL improved from baseline to 6 months as assessed by the Living with Heart Failure questionnaire (from 54 +/- 18 to 19 +/- 7, P = 0.029). Mean LV ejection fraction improved from 35 to 40% at Day 5 and to 44% at 6 months (P = NS). The LV end diastolic and end systolic volumes decreased (220-202 ml, 159-130 ml, P = NS) at 6 months. Global end-systolic strain improved from -7.3% at baseline to -8.5% at Day 5 and -8.8% at 6 months (P = NS). Regional LV function and response to IA was not uniform. Even without IVIG substitution, IA for the treatment of chronic DCM is associated with improved QOL up to 6 months after treatment. A randomized, sham-controlled trial is required to confirm the benefits of IA for DCM.

Selective immunoclean-up followed by liquid chromatography for the monitoring of a biomarker of exposure to polycyclic aromatic hydrocarbons in urine at the ngl−1 level

A selective clean-up procedure using an immunosorbent (IS) was developed for the trace-level determination, in water and urine samples, of 3-benzo(a)pyrene-glucuronide (3-BP-G), a biomarker of exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs). First, three sorbents used for the immobilization of antibodies were evaluated for their ability to limit the risk of non-specific interactions and to provide a high bonding density. The best sorbent, i.e. sepharose, was used for the immobilization of two different monoclonal antibodies. The most specific antibody for 3-BP-G was applied to the selective extraction from urine providing a clean extract, an easy and reliable quantification by comparison with a classical SPE process. The sensitivity of the fluorescence associated with the selectivity of the IS provides a limit of detection up to 1.2 ng l(-1) in urine for 3-BP-G.

A Serial Copolymerization Procedure for Manufacturing Immunoadsorption Walls as a Potential Unit in Conjunction With Hemodialysis Filters

A functional immunoadsorption wall for removal of beta-2-microglobulin has been made by partially incomplete two-stage copolymerization of acrylamide with immunoadsorbent. However, a substantial amount of immunoadsorbent needs to be flushed away after the copolymerization process. Thus, to enhance the utilization efficiency of immunoadsorbent, the flushed-away immunoadsorbent was further recovered, and the copolymerization was conducted in series to produce three consecutive immunoadsorption walls in this study. Preliminary removal tests show that similar removal patterns were obtained for these immunoadsorption walls. Although it is not timely to conclude that a clinically applicable immunoadsorption wall has taken shape, the development of a partially incomplete two-stage polymerization method and its associated techniques indeed provide a good basis for large-scale manufacturing immunoadsorption walls.

Development and Characterization of a New Stationary Phase for an Immunoadsorption Wall

This study introduces a newly developed method for the formation of a stationary phase superficially embedded with immunoadsorbent, that is partially incomplete two-stage polymerization of acrylamide. Preliminary experimental studies show that binding activity of the immunoadsorbent was satisfactorily maintained after immobilization. With an appropriate configuration of selected immunoadsorption matrices and immunoisolation barriers, it is hoped that this stationary phase could be used to resolve some difficult problems arising from the accumulation of certain middle molecular weight toxins not removed by other blood purification procedures.

New Approaches to the Formation of a Stationary Phase in an Immunoadsorption Wall

The concept of an immunoadsorption wall, which combines the principles of immunoisolation and immunoadsorption, was proposed in 1999 to remove certain toxins accumulated in patients' blood. However, realization of this concept is obviously handicapped by the inefficient use of immunoadsorbent. This study is intended to improve the use of immunoadsorbent and optimize the formation of a stationary phase in an immunoadsorption wall. Polyacrylamide gel, which has the advantages of being chemically inert, having minimal diffusion effect and reasonable cost, could be considered as the medium of choice for a stationary phase. In this study, new approaches aimed at effective allocation of immunoadsorbent utilizing polyacrylamide gel are attempted. The advantages and disadvantages of these new approaches are discussed according to the preparation, formation, and outcome of a stationary phase. It is hoped that these new approaches could serve as a first step toward building an immunoadsorption wall.

Changes of plasma proteins after immunoadsorption using Ig-Adsopak columns in patients with myasthenia gravis

BACKGROUND AND OBJECTIVES

Ig-Adsopak immunoadsorption columns were used for treatment to determine their influence on the amount of immunoglobulins and other plasma proteins.

PATIENTS AND METHODS

Patients with myasthenia gravis were treated, 178 immunoadsorption procedures were performed. The mean plasma volume treated in a 2-4 week interval was 3600 ml. Plasma protein concentrations were measured prior to and after each treatment. The concentration of anti-acetylcholine receptor antibodies was also measured.

RESULTS

The amounts of the IgG, IgM and IgA removed were respectively, 55.7%, 42.8% and 43.4% of the initial level whereas the other plasma proteins were found to bind with a lower affinity with only 19.8% removal. 60.9% of the anti-acetylcholine receptor antibodies were removed.

CONCLUSIONS

Ig-Adsopak columns have a semi-specific effect on the plasma proteins, mostly on immunoglobulins of all classes.

Cytokine Adsorptive Property of Various Adsorbents in Immunoadsorption Columns and a Newly Developed Adsorbent: An in vitro Study

BACKGROUND/AIMS

Cytokines play important roles in the pathophysiology of systemic inflammatory response syndrome (SIRS) and sepsis. Therefore, some effective measures to remove cytokines from the bloodstream could be effective in the treatment of SIRS and sepsis. The aim of this study was to evaluate the cytokine adsorptive property of various adsorbents for the purpose of the development of new selective cytokine adsorption columns.

METHODS

The cytokine adsorptive property of adsorbent in a CF-X column, which consists of cellulose beads cross-linked with hexamethylene-di-isocyanate, was compared with those of various adsorbents in currently available immunoadsorption columns, such as Immusorba TR, Immusorba PH, Selesorb, and Lixelle, in vitro batchwise test using patients' plasma. A newly developed adsorbent, MPCF-X, which was modified by coating the surface of the adsorbent in CF-X with 2-methacryloyloxyethyl phosphorylcholine (MPC), was also tested for its cytokine adsorptive property.

RESULTS

The adsorbent in CF-X showed a significantly higher adsorption rate for TNF-alpha, interleukin (IL)-6 and IL-10 compared with other adsorbents (p < 0.05). Adsorbent in Lixelle showed good affinity to TNF-alpha and IL-8. Especially, the adsorbent in CF-X almost completely removed TNF-alpha, whereas it also had considerable affinity to normal IgG. MPCF-X showed decreased affinity to IgG with considerable adsorptive properties to cytokines.

CONCLUSION

Selective cytokine adsorption columns could be developed with improvement of currently available adsorbents. Such a new selective cytokine adsorption column could be clinically applied for the treatment of SIRS/sepsis.

Magnetoelastic Immunosensors: Amplified Mass Immunosorbent Assay for Detection of Escherichia coli O157:H7

A mass-sensitive magnetoelastic immunosensor for detection of Escherichia coli O157:H7 is described, based on immobilization of affinity-purified antibodies attached to the surface of a micrometer-scale magnetoelastic cantilever. Alkaline phosphatase is used as a labeled enzyme to the anti-E. coli O157:H7 antibody, amplifying the mass change associated with the antibody-antigen binding reaction by biocatalytic precipitation of 5-bromo-4-chloro-3-indolyl phosphate in a pH 10.0 PBS solution. The detection limit of the biosensor is 10(2) E. coli O157:H7 cells/mL. A linear change in the resonance frequency of the biosensor was found to E. coli O157:H7 concentrations ranging from 10(2) to 10(6) cells/mL.

Development of an in vitro miniature model to simulate immunoadsorption in patients with systemic lupus erythematosus

In SLE, immunoadsorption is used as an adjuvant therapy; however, adsorption profiles and binding mechanisms have not yet been completely investigated. Using a minicolumn filled with the sorbent IMPH with or without the ligand phenylalanine, we developed a model simulating clinical conditions in a reduced scale with a constant ratio of plasma to column volume and a constant plasma flow at room temperature. By desorbing the column, the adsorption efficacy for different antibodies could be measured directly. We demonstrate that the adsorption rate can be increased by a low plasma flow and by covering the column surface. Double perfusion of the same column did not increase the amount of adsorbed antibodies. We further demonstrate that the carrier material without a ligand is unable to bind antibodies or protein. In the IMPH sorbent anti-dsDNA antibodies were significantly better adsorbed than total IgG or total protein. After a single perfusion of 21 samples, we estimated a mean anti-dsDNA antibody adsorption rate of 22.5% (+/-13.6). A group of ten responders with a medium adsorption rate of 35.4% (+/-6.5) clearly differed from a second group of eleven nonresponders (10.9% +/- 4.2). Anti-cardiolipin antibodies (ACA) were adsorbed in a wide range (IgG type, 2.5-52.7%, IgM type, 1.1-37.8%) while anti-Ro (SSA) antibody adsorption was negligible. This in vitro minimodel provides a precise simulation of therapeutic immunoadsorption and helps to analyze the binding characteristics of the sorbent IMPH and shows its effectiveness in several antibody subsets of different patients.

Immunoaffinity beads for selective removal of cholesterol from human plasma

Anti-low density lipoprotein antibody (anti-LDL antibody) attached poly(2-hydroxyethyl methacrylate-methacryloylamidophenylalanine) (poly(HEMA-MAPA)) beads were prepared for selective removal of cholesterol from hypercholesterolemic human plasma. Poly(HEMA-MAPA) beads were produced by a modified suspension polymerization and then characterized by swelling tests and SEM. Blood-compatibility tests were also investigated. The water swelling ratio of the poly(HEMA-MAPA) beads increased significantly (68%) compared with pHEMA (55%). All the clotting times increased when compared with poly(HEMA) beads. Loss of platelets and leukocytes was very low. The maximum anti-LDL antibody attachment was achieved at pH 7.0. Attachment of anti-LDL antibody was 29.6 mg/g. There was a very low non-specific cholesterol binding onto the poly(HEMA-MAPA) beads, about 0.74 mg/g. Anti-LDL antibody attached beads adsorbed in the range of 13.3-16.0 mg cholesterol/g from hypercholesterolemic human plasma. Up to 92% of the adsorbed LDL was desorbed. The binding-elution cycle was repeated 10 times using the same beads. There was no significant loss of binding capacity.

Peptide based adsorbers for therapeutic immunoadsorption

Peptides as ligands for immunoadsorption exhibit several potential advantages over native proteins. Two newly developed adsorbers are based on peptides covalently coupled to sepharose CL-4B. Globaffin is capable of binding immunoglobulins independent from their antigen specificity and thus, applicable in transplant recipients and several antibody mediated autoimmune diseases. Among others, the most important disorders suitable for the treatment with Globaffin are rheumatoid arthritis, systemic lupus erythematosus, and acute renal transplant rejection. Coraffin is a specific adsorber using two linear peptide ligands mimicking epitopes of the beta1-adrenergic receptor, that bind corresponding autoantibodies from patients suffering from idiopathic dilated cardiomyopathy. Specific immunoadsorption has been shown to be beneficial for patients with dilated cardiomyopathy. Coraffin can be used as a new therapeutic option for these patients, who get only limited benefit from medical therapy. Both adsorbers may be combined with all approved apheresis control devices available.

Immusorba TR and PH

Immusorba TR (IM-TR) and PH (IM-PH) were developed as adsorbents with non-biological materials as affinity ligands to remove pathogenic autoantibodies. The adsorbents of IM-TR and IM-PH are polyvinyl alcohol gel immobilized with tryptophan and phenylalanine as ligand, respectively. IM-TR is clinically applied for treatment of autoimmune neurological diseases such as myasthenia gravis and Guillain-Barre syndrome. IM-PH is used for not only neurological diseases such as GBS and multiple sclerosis but also collagen diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). As many autoantibodies with different specificities have been found to have similar affinities to the ligand of Immusorba, it is expected that Immusorba will be applied to more diseases and contribute to the clarification of the mechanisms of the development of diseases by the identification of adsorbed unknown pathogenic substances with Immusorba.

Adsorption column for myasthenia gravis treatment: Medisorba MG-50

Adsorption column Medisorba MG-50 (Kuraray Medical Inc.) for the treatment of myasthenia gravis (MG) is introduced. The adsorbent in this column is composed of cellulose beads as carrier material and covalent-bound synthetic peptide as a ligand that has a specific affinity to the pathogenic anti-acetylcholine receptor antibody of MG. The amino acid sequence of the peptide is modified from the segment of alpha 183-200 of the torpedo acetylcholine receptor (AChR) protein, and the segment is the acetylcholine binding site on AChR and the target site of anti-AChR antibody. The adsorbent showed specific adsorption characteristics to the anti-ACHR antibody (blocking antibody) in vitro. Clinically, MG-50 is used in plasma-perfusion therapy, and it is recognized that MG-50 specifically reduces blocking antibody titer and improves MG symptoms. MG-50 is approved in Japan.

Determination of microcystins in lake water using reusable immunoaffinity column

A reusable immunoaffinity column for purification of microcystins in lake water was prepared by coupling anti-microcystin-LR monoclonal antibodies to immunoaffinity support. Thanks to spherical shape of the immunoaffinity support Formyl-Cellulofine used in this study, applied solutions passed the column smoothly even when used repeatedly. Reusability of the column was examined by determining the recoveries of spiked microcystins-RR, -YR and -LR (100ng each) from lake water. After extraction with a Sep-Pak PS2 cartridge containing styrene-divinylbenzene copolymer, the extract was purified with the immunoaffinity column. The immunoaffinity column was regenerated by washing with Tris-HCl buffer containing bovine serum albumin for repeated uses. Recoveries of spiked microcystins from the first use of the column were 87-88%, and 83-88% from the second and third uses, and the recoveries gradually dropped to 63-77% from the 4-5th uses, the results of which indicated that the column could be used repeatedly for three times. The present method was applied to determine microcystins in water collected from three different lakes in Japan in 1999. In a sample from Lake Suwa, microcystins-RR and -LR were determined by high performance liquid chromatography with photodiode array detection and electrospray ionization-liquid chromatography/mass spectrometry.

Risk of hepatitis C after immunoadsorption

An episode of acute hepatitis in a patient with hemophilia during immunoadsorption therapy initially was misinterpreted as a reactivated hepatitis C virus (HCV) infection, but ultimately was shown to be an exogenous reinfection during cohort treatment with another HCV-positive patient. This incident illustrates that policies for the prevention of nosocomial transmission of blood-borne pathogens, especially in cohort treatment units, may need to be reassessed.

Stirrer tank: an appropriate technology to immobilize the CB.Hep-1 monoclonal antibody for immunoaffinity purification

The CB.Hep-1 monoclonal antibody was coupled to CNBr-activated Sepharose CL 4B at three different immobilization scales for purification of recombinant hepatitis B surface antigen. Standard laboratory apparatus to obtain immunosorbents of 1 l (scale I) and 3 l (scale II) as well as a stirrer tank to prepare 6 l immunosorbents (scale III) were used. The binding capacity at scale III was 2- and 1.5-fold higher with respect to the scales II and I, while a reduction in the ligand leakage of 5- and 2-folds was observed. Immunosorbents from scale II showed a significantly reduced adsorption, and an increased ligand leakage. Differences in the coupling efficiency were not observed. Antigen purity eluted from the immunosorbents was always above 85%.

A novel immunoadsorption device for removing beta2-microglobulin from whole blood

BACKGROUND

High plasma levels of beta2-microglobulin (beta2m) have been implicated in the formation of the severely destructive and potentially fatal amyloid deposits that are characteristic of dialysis-related amyloidosis (DRA). Conventional renal replacement technologies remove insufficient quantities of beta2m to normalize plasma levels. This limitation arises because of nonspecific adsorptive qualities and reliance on size exclusion, which can also remove other middle molecular weight proteins. These nonspecific approaches also make it difficult to evaluate the role and contribution of middle molecular weight molecules to the pathology of DRA and other morbidities of end-stage renal disease. A high-affinity and biologically specific approach could target a protein, prevent a significant loss of other important molecules, and improve the apparent adsorption rate within an extracorporeal device.

METHODS

Agarose-immobilized murine anti-human beta2m monoclonal antibodies were used in a Vortex Flow Plasmapheretic Reactor (VFPR) to remove donor baseline and controlled amounts of recombinant beta2m from human blood in vitro. The extracorporeal circuit was hemoperfused at 200 mL/min for two hours.

RESULTS

The immunoadsorptive media had a binding site density of 30 microg beta2m per mL of settled gel. The VFPR cleared baseline quantities of donor beta2m below detectable limits of the assay. The experiments with higher initial beta2m concentrations reached an equilibrium concentration within 20 minutes, corresponding to a 92% clearance. No deleterious hemocompatibility issues were observed (complete blood count, total protein, and plasma free hemoglobin).

CONCLUSIONS

The adsorptive kinetics of the VFPR are optimal for the conditions used and support the use of immunoadsorption for the removal of beta2m.

In vitro characterization of a membrane-based low-density lipoprotein affinity adsorption device

The objective of this study was to explore the use of microporous membranes as an alternative substrate to porous beads in affinity adsorption of low-density lipoprotein (LDL) for therapeutic purposes. Flat sheet immunoaffinity membranes containing a polyclonal antibody preparation were utilized as the affinity substrate. The antibody was covalently immobilized to the surface through a poly(ethylene glycol) (PEG) spacer. Equilibrium adsorption of LDL from plasma was measured. Adsorption from plasma and elution of bound LDL using citrate buffer were studied as a function of flow rate. Specific capacity was as great as 2 mg apolipoprotein B per milliliter membrane volume. The superior transport properties of the membrane allowed rapid adsorption and regeneration, which translated to a large number of adsorptive cycles that can be performed within a given treatment time. On the basis of in vitro performance characteristics, it is estimated that an immunoaffinity membrane device can provide a reduction in patient plasma LDL concentration comparable to that provided by packed columns, but with almost an 80% reduction in the device volume.

Local anticoagulation of the extracorporeal circuit with heparin and subsequent neutralization with protamine during immunoadsorption

A regimen of local anticoagulation of an immunoadsorption device was studied. The extracorporeal circuit was anticoagulated with citrate (5.5%) and a continuous infusion of heparin (2,000 U/h or 1,500 U/h), which was neutralized by a continuous infusion of protamine chloride (75% of the heparin dose) before reinfusion in 23 patients treated with low-density lipoprotein or immunoglobulin apheresis. Sufficient anticoagulation of the extracorporeal circuit was obtained (activated partial thromboplastin time [APTT] > 180 seconds; thrombin time [TT] > 120 seconds; anti-Xa activity, 1.05 +/- 0.21 U/mL) during the entire treatment of 190 minutes, whereas coagulation parameters in the patients' blood stayed within the normal range. In a control group without heparin neutralization, full systemic anticoagulation of the patients occurred (APTT, 157.8 +/- 30.6 seconds; TT, 119.8 +/- 0.4 seconds; anti-Xa activity, 0.88 +/- 0.21 U/mL). No side effects or clotting of the system were observed. Our data show that this regimen of local anticoagulation is a safe protocol for extracorporeal circulation without exposing the patients to anticoagulants.

Adsorption of anaphylatoxins from the plasma of systemic lupus erythematosus patients using dextran sulfate cellulose columns

Complement-derived anaphylatoxin may be one of the causes of vascular injury and an indicator of activity in systemic lupus erythematosus (SLE). The present study examines the effectiveness of dextran sulfate (DS) column immunoadsorption treatment to remove anaphylatoxins (C3a, C4a, and C5a) from the blood of patients with SLE. Seven SLE patients were subjected to immunoadsorption using DS-bound cellulose columns (Selesorb, Kaneka). Blood samples were taken both before and after the immunoadsorption session. Specimens were also obtained from both the inlets and outlets of the DS columns every 1,000 ml of treated plasma volume. The DS columns removed anaphylatoxins C3a and C4a from the separated plasma (from 775+/-334 ng/ml to 640+/-252 ng/ml, and from 1,303+/-847 ng/ml to 619+/-578 ng/ml, respectively) during the clinical anti-DNA apheresis procedure. In these study, the C5a levels in the circulating plasma of SLE patients were not elevated. To confirm whether DS-bound cellulose beads adsorbs anaphylatoxins in vitro, zymosan-activated plasma (ZAP) containing high levels of anaphylatoxins was incubated with DS-bound cellulose beads. The levels of C3a, C4a and C5a in the ZAP significantly decreased by mixing with DS-bound cellulose beads (P<0.05). Nevertheless, C3a and C4a in the peripheral blood were not significantly decreased after the immunoadsorption, suggesting that these anaphylatoxins bypass the DS columns in apheresis and return to the patient via the cell-rich fraction.

Immunoadsorption in dilated cardiomyopathy

The prognosis for patients suffering from advanced stages of dilated cardiomyopathy (DCM) is poor. Recent studies have shown that immunoadsorption (IA) may represent an effective alternative therapeutic approach for other kinds of autoimmune diseases with circulating autoantibodies. The objective of this pilot study was to ascertain the short-term hemodynamic effects of IA in patients with idiopathic DCM and circulating autoantibodies. Our study included 9 patients with circulating beta1-adrenoreceptor antibodies who suffered from idiopathic DCM as well as severe heart failure (left ventricular ejection fraction <30%). Immunoadsorption was performed on 5 consecutive days using an adsorber against immunoglobulins (Ig Therasorb, Baxter, Unterschleissheim, Germany). Substitution of 0.5 g/kg of polyclonal immunoglobulin took place after the final IA session. During IA, the cardiac index and stroke volume index increased from 2.0+/-0.42 to 2.9+/-0.79 L/min(-1)/m(-2), p < 0.01, and from 24.0+/-7.4 to 35.9+/-10.3 ml/m2, p < 0.05, respectively. In addition to drug therapy, IA may represent a promising alternative therapeutic possibility for hemodynamic stabilization of patients with severe idiopathic DCM.

The role of immunoadsorption using dextran-sulfate cellulose columns in the treatment of systemic lupus erythematosus

Immunoadsorption using dextran sulfate (DS)-cellulose columns is reviewed. An extracorporeal selective adsorption system using such columns has been developed and clinically used to remove anti-DNA from the circulating blood of systemic lupus erythematosus (SLE) patients. These columns can adsorb pathogenic anti-DNA subgroups of high avidity and/or cationic antibodies, anticardiolipin, anti-CLbeta2GPI, and anaphylatoxins. An open clinical study on 19 SLE cases (the mean number of apheresis sessions totaled 3.7 times; the mean dose of prednisolone, 38 mg/day) revealed that the mean SLE disease activity index (SLEDAI) score significantly decreased from the pretreatment level of 10.2 to 4.5 after treatment. Several case reports have indicated that this modality might also be useful for treating patients with antiphospholipid syndrome. Compartment model analyses showed the one-compartment model to be the most suitable for the kinetics of anti-DNA during and following the apheresis procedure. The indications for immunoadsorption in the treatment of SLE remain controversial. A steroid-sparing effect might be one of them, but further controlled studies are necessary to verify this hypothesis.

Immunoadsorption in Guillain-Barré syndrome and myasthenia gravis

Elimination of circulating antibodies by hemapheresis is an empirical treatment concept in various neuroimmunological diseases. Plasma exchange (PE) has been shown to be superior to symptomatic treatment in Guillain-Barré syndrome (GBS) in two large multicenter studies. It is also effective in myasthenia gravis (MG), although no comparative studies have been performed. Immunoadsorption (IA) using polyvinyl alcohol gel columns to which phenylalanin (IM-PH) or tryptophan (IM-TR) are covalently bound is an alternative to PE, and seems to have equal efficacy and comparable side effects. This method also obviates the need for replacement of plasma with human albumin or plasma. We compared the treatment results of 11 patients with GBS treated by PE to those of 13 patients treated by IA using an IM-TR column. Here, we found no statistically significant differences with regard to efficacy and clinical or procedural complications. From these data we conclude that immunoadsorption can be used as an equal alternative to PE. A large multicenter study comparing PE, intravenous immunoglobulins (IVIG), and the combination of both in the treatment of GBS revealed no significant difference between the 3 treatment groups. In MG, only 2 small studies have been performed using IA, and no studies comparing PE or other treatments to IA have been conducted. Both investigations of IA therapy demonstrated a marked reduction in the acetylcholine receptor (AchR) antibodies and a sustained improvement of the clinical signs. These results therefore show that IA is an effective treatment for myasthenia gravis.

Low density lipoprotein apheresis in treatment of hyperlipidemia: experience with four different technologies

The prognosis of patients suffering from severe hyperlipidaemia (HLP), sometimes combined with elevated lipoprotein (a) levels, and coronary heart disease (CHD) refractory to diet and lipid lowering drugs is poor. A new therapeutic option for such patients is regular treatment with low density lipoprotein (LDL) apheresis. In total 33 patients (16 males, 17 female, aged 43.8+/-14.3 years), suffering from severe HLP resistant to diet and lipid lowering drugs, were treated for 62.3+/-21.3 (range, 1-113) months with LDL-apheresis. Four different LDL-apheresis systems were used: the dextran sulfate adsorption for 28 of 33 (Liposorber, Kaneka, Japan), immunoadsorption for 2 of 33 (Therasorb, Baxter, Germany), LDL-hemoperfusion for 2 of 33 (Dali, Fresenius, Germany), and the immunoadsorption system with special antilipoprotein (a) columns for 1 of 33 patients (Lipopak, Pocard, Russia). Before applying LDL-apheresis, 27 of 33 patients suffered from CHD with severe angina pectoris symptoms, a history of myocardial infarction or coronary artery venous bypass (CAVB). With LDL-apheresis, reductions (p < 0.05) of 46% for total cholesterol, 49% for LDL, 28% for Lp(a), and 38% for triglycerides were reached. Severe side-effects, such as shock or allergic reactions, were very rare (0.5%). In the course of treatment an improvement in general well-being and increased performance were experienced in 29 of 33 patients. In 23 of 27 patients suffering from CHD, a reduction of 60 to 100% of nitrate medication was observed. Regarding the different apheresis systems used, there were no significant differences with respect to the clinical outcome and concerning total cholesterol, LDL, HDL, and triglyceride concentrations. But, in respect to elevated lipoprotein (a) levels, the immunoadsorption method using special anti-lipoprotein (a) columns seems to be the most effective (-57% versus -25% [Kaneka, p < 0.05] or -23% [Baxter, p < 0.05]). The present data clearly demonstrate that treatment with LDL-apheresis in patients suffering from severe HLP, refractory to maximum conservative therapy, is effective and safe in long-term application.

Neutrophil activation in immunoadsorption

Immunoadsorption therapy (IAT) is used in the treatment of autoimmune diseases. Although IAT has been reported to modify humoral immunity by inducing chemokines and activating complements, much remains unknown about the biological effects of IAT on cellular components in peripheral blood. To define the influence of IAT on leukocytes, we determined leukocyte L-selectin (CD62L) and Mac-1 (CD11b) as parameters for activation of leukocytes in peripheral blood during IAT. Peripheral leukocyte L-selectin and Mac-1 were determined continuously by flow cytometry in 6 patients with neuroimmunological disorders in whom IAT was conducted using a Plasma Flow OP-05 (Asahi Medical Corp., Tokyo, Japan) as a plasma separator and Immusorba TR-350 (Asahi Medical Corp., Tokyo, Japan) as an adsorption column. Expression of neutrophils (PMN) L-selectin was decreased 30 min after starting IAT, with the decreases particularly marked at the end of IAT, while expression of mononuclear cells (MNC) L-selectin slightly increased during IAT. Expression of PMN Mac-1 was markedly increased at the end of IAT, whereas expression of MNC Mac-1 did not change during IAT. Leukocyte counts decreased 30 min after starting IAT, and then increased to the initial level or higher in parallel with L-selectin downregulation and Mac-1 upregulation on PMN. L-selectin downregulation and Mac-1 upregulation on PMN suggested that activation of PMN associated with changes in peripheral leukocyte counts occurred during IAT and might play some role in modulating the human circulating blood and immune systems.

Apheresis and selective adsorption plus immunoglobulin treatment in Guillain-Barré syndrome

Plasma exchange (PE) and administration of intravenous immunoglobulin (i.v. IgG) are established treatments for Guillain-Barré syndrome (GBS). Combination treatment with elimination of postulated pathogenetic factors by PE or selective adsorption (SA) treatment and subsequent immunomodulation by intravenous IgG may provide a more effective treatment. In a single-center randomized study, 45 patients with acute GBS were prospectively examined using a clinical score. We treated 11 patients by PE, 13 with SA using a tryptophan-linked polyvinyl alcohol gel adsorbent, and 21 with SA followed by intravenous IgG. The patients treated sequentially by selective adsorption and intravenous IgG improved significantly better than the patients who received plasma treatment only. The results suggest that combination treatment of GBS may be superior to plasma treatment alone.

Immuno affinity purification of foot and mouth disease virus type specific antibodies using recombinant protein adsorbed to polystyrene wells

The specificity of foot and mouth disease virus (FMDV) serological tests depends largely on the quality and purity of the antibodies used. Such type specific antibodies can be generated by hybridoma technology. Alternatively, the specific antibodies can be selected from polyclonal serum by immunoaffinity chromatography using recombinant protein/peptide bound affinity matrices. Based on this approach, we purified selectively antibodies against the major epitopes of VP 1 of FMDV serotype Asia 1 using recombinant protein adsorbed to polystyrene wells. Optimum buffer conditions were standardised for efficient elution. Buffer consisting of 4 M MgCl2 with 75 mM HEPES pH 6.5 was found to be optimum with respect to elution efficiency of bound antibodies and integrity of antigen. The specific reactivity of eluted antibodies was confirmed by dot-enzyme linked immunosorbent assay (dot-ELISA) and antigen capture reverse transcription polymerase chain reaction (Ag/RT-PCR). The effect of temperature and repeated elution on the stability of coated protein were studied.

The removal of beta-2-microglobulin by an immunoadsorption wall

The accumulation of beta-2-microglobulin (beta2M) in collagen-rich tissues has been proven to be the main cause of dialysis related amyloidosis. However, it remains uncertain which technique for the removal of beta2M can be used without compromising the advantages of other dialysis strategies. A new concept, an immunoadsorption wall, which combines the principles of immunoisolation and immunoadsorption is proposed to remove beta2M. The present investigations suggested that the application of the concept to clinical use is feasible and worthwhile. The concept, if validated, will help shape a novel multitask type of artificial kidney based on the combination of different separation technologies.

Immusorba TR and Immusorba PH: basics of design and features of functions

Immusorba was reported by Yamazaki et al. to be the world's first practical immunoadsorbent in 1982. Since then, this immunoadsorbent has accumulated an abundance of clinical achievements. Immusorba has such unique functions that it is used in treating various diseases and holds possibilities for application to more diseases. Immusorba was designed as an artificial receptor for rheumatoid factor (RF) based on structural analysis of heat-denaturated globulin. Subsequently, new substances that it can adsorb have been found as seen in reports on the adsorption performance of Immusorba to anti-acetylcholine receptor antibodies (anti-AChR Abs) and antiganglioside antibodies. Along with this, Immusorba has been used in treating a wide range of diseases. The greatest characteristic of Immusorba is that its adsorption capability is selective rather than specific, making it effective against a great number of diseases.

Ability to remove immunoglobulins and anti-ganglioside antibodies by plasma exchange, double-filtration plasmapheresis and immunoadsorption

In Japan, patients with Guillain-Barré (GBS) and Fisher's (FS) syndromes often receive plasma exchange (PE), double-filtration plasmapheresis (DFPP), or immunoadsorption (IA). To determine whether DFPP and IA are as effective as PE, we compared their abilities to remove immunoglobulins and anti-ganglioside antibodies. Plasma samples were obtained from 55 GBS patients and 53 FS patients, before and after each session of the treatments. PE decreased the IgG concentration more than DFPP did, its abilities to remove anti-ganglioside IgG antibodies in PE markedly being superior to the abilities of the other plasmaphereses. IA on a tryptophan-immobilized column adsorbed anti-ganglioside IgG antibodies more effectively than IA on other affinity columns.

Competitive immunosorbent assays using ligand-enzyme conjugates bifunctional liposomes: theory and experiment

Two models of immunoadsorbent assays are developed that describe the competitive adsorption of labeled antigen and unlabeled analyte to antibody binding sites immobilized on a solid surface. In the first model, a small labeled antigen and a small unlabeled analyte compete with only binding site limitations and no steric limitations. A multicomponent langmuir isotherm results that is sufficient to quantify competitive adsorption. This model can describe, with no adjustable parameters, the data of competitive assays for biotin using biotinylated horseradish peroxidase (B-HRP) over a wide range of anti-biotin antibody (ABA) surface densities. In the second model, the small unlabeled analyte competes with a large colloidal particle containing many antigens and enzyme labels attached to its surface. This model quantifies the steric interference that large particles can experience upon binding (large ligand effect) due to the lower probability of finding an available area of the right size to accommodate the larger adsorbent. This large ligand model also takes into account the increased probability of binding a large particle due to the larger number of antibody binding sites covered per collision. The resulting model is used to analyze the competitive assay data of biotin competing with liposomes to which many biotin and HRP molecules have been conjugated. This analysis is of interest because previous work has shown that these bifunctional liposomes can reduce the detection limit for antigens in bulk solution relative to assays performed with conventional small labeled antigens.