Presence Of Fc Research Articles

Redox active metallene anchored amino-functionalized cellulose composite for electrochemical capture and conversion of chromium

Considering the ubiquity and high toxicity of Cr(VI) species for destroying a sustainable environment, developing energy-efficient method for capturing and detoxifying chromium [Cr(VI) → Cr(III)] is imperative. Herein, ferrocene (Fc) was combined with carboxymethyl cellulose (CMC) and polyethyleneimine (PEI) for Cr(VI) remediation. Fc species possessed reversible redox behavior and low ionization potential, yet it faced challenges with conductivity and stability. Results revealed that, PEI facilitated the binding of Fc within the CMC through electrostatic interactions or coordination bonds, ensuring the good dispersion and stability of Fc. When applied in the electrochemical adsorption of Cr(VI), the combination created a synergistic effect. The presence of Fc and PEI boosted the electrochemical performance by providing faster electronic and ionic transportation, higher specific capacitance coupled with improved electrode-electrolyte interactions, leading to a higher Cr(VI) adsorption capacity over CMC/PEI/Fc (280.5 mg/g) compared to those over CMC and CMC/PEI. The interactions between the Cr(VI) and electrode included the electrosorption, electrostatic interaction of protonated PEI and oxidized Fc species. When the electric field was reversed, the Cr(VI) was electrostatic repulsed and electrocatalytic reduced to Cr(III) with a reduction rate of 85.4 %. This work promoted the development of effective electrosorption materials suitable for complete Cr(VI) removal and detoxification.

Sorption characteristics of phosphorus on marine sediments in the presence of black carbon derived from fly ash

The sorption behavior of phosphorus on marine sediments in the presence of black carbon derived from fly ash (FC) was studied. For both the FC and sediment samples, the kinetic curves could be described by a two-compartment first order equation, and the isotherms fit the Freundlich and Langmuir models well. The high specific surface area with abundant acidic functional groups of FC promoted the sorption and make this process more irreversible. The effects were more significant with higher amount of FC added. After sorption, more significant increase in Ex-P, Fe/Al-P and CaP was found in the sediment with FC added, while the organic groups in FC rarely react with phosphorus to form OP. The pH of medium influenced the sorption character, and FC promoted the process significantly at pH < pHPZNPC. The sorption was endothermic with an increase in randomness. The presence of FC had little effects on the thermodynamic parameters.

Oxidation Enhances Binding of Extrahelical 5-Methyl-Cytosines by Thymine DNA Glycosylase.

The DNA repair protein thymine DNA glycosylase (TDG) removes mispaired or damaged bases, such as oxidized methyl-cytosine, from DNA by cleavage of the glycosidic bond between the sugar and the target base flipped into the enzyme's active site. The enzyme is active against formyl-cytosine and carboxyl-cytosine, whereas the lower oxidized hydroxymethyl-cytosine and methyl-cytosine itself are not processed by the enzyme. Molecular dynamics simulations with thermodynamic integration of TDG complexed to DNA carrying one of four different (oxidized) methyl-cytosine bases in extrahelcial conformation, methyl-cytosine (mC), hydroxymethyl-cytosine (hmC), formyl-cytosine (fC), or carboxyl-cytosine (caC), show a more favorable binding affinity of the higher oxidized forms, fC and caC, than the nonsubstrate bases hmC and mC. Despite rather comparable, reaction-competent conformations of the flipped bases in the active site of the enzyme, more and stronger interactions with active site residues account for the preferred binding of the higher oxidized bases. Binding of the negatively charged caC and the neutral fC are strengthened by interactions with positively charged His151. Our calculated proton affinities find this protonation state of His151 the preferred one in the presence of caC and conceivable in the presence of fC as well as increasing the binding affinity toward the two bases. Discrimination of the substrate bases is further achieved by the backbone of Tyr152 that forms a strong hydrogen bond to the carboxyl and formyl oxygen atoms of caC and fC, respectively, a contact that is completely lacking in mC and much weaker in hmC. Overall, our computational results indicate that the enzyme discriminates the different oxidation forms of methyl-cytosine already at the formation of the extrahelical complexes.

Proteolytic profile, angiotensin-I converting enzyme inhibitory activity and sensory evaluation of Codonopsis pilosula and fish collagen cheese

Four types of cheeses were prepared included plain- cheese (control), Codonopsis pilosula (CP)- cheese, plain- cheese with fish collagen (FC; control) and CP- cheese with FC. The effects of cheese samples on acidification, proteolysis of milk proteins using three methods (cadmium-ninhydrin method, O-phthaldialdehyde (OPA) assay, and electrophoresis assay), and angiotensin-converting enzyme (ACE)-inhibitory activity were investigated during 0, 2, & 4 weeks of ripening. In addition, the sensory evaluation was also investigated during 0, 2, 4, & 8 weeks of ripening. The presence of FC in CP- cheese increased the numbers of free amino acids (FAA) at 0 and 2 weeks. The addition of CP both in the presence and absence of FC affected positively (p < 0.05) on the concentrations of OPA peptide in cheese compared to their respective controls. The presence of CP and/or FC in cheese increased the degradation of milk proteins (α-, β-, & κ- caseins, β-lactoglobulin, and α-lactalbumin) compared to their respective controls during ripening periods. The highest ACE inhibitory activity was shown at 4 weeks of ripening for CP- cheese both in the absence (67.75 ± 14.15%) and the presence (78.65 ± 2.85%) of FC. In addition, 8-week-old CP-cheese in the presence and absence of fish collagen had similar organoleptic characteristics to plain-cheese. In conclusion, C. pilosula and/or fish collagen may lead to the development in the production and formulation of cheese with anti-ACE activity.

Electrocatalytic properties of a dinuclear cobalt(III) coordination compound in molecular oxygen reduction reaction

A new dinuclear cobalt(III) coordination compound, [Co2L(μ‐N3)(N3)2]·CH3OH (1), was synthesized and characterized by elemental analysis, spectroscopic methods, and single‐crystal X‐ray analysis in which H3L is a heptadentate ligand obtained by the condensation of triethylenetetramine with 5‐bromo‐2‐hydroxybenzaldehyde. X‐ray analysis revealed that two cobalt(III) ions have distorted octahedral geometry and are connected together by a phenoxy and an azide bridging ligand. The catalytic activity of compound 1 for oxygen (O2) reduction reaction was investigated. Compound 1 can efficiently catalyze the reduction of O2 by a weak electron donor, ferrocene (Fc), at the polarized water–1,2‐dichloroethane interface. It was found that compound 1 can catalyze O2 reduction to H2O2, whereas in the presence of Fc, it can catalyze the reduction of O2 to water.

Synthesis, characterization and electrochemical evaluation of a novel high performance GO-Fc/PANI nanocomposite for supercapacitor applications

A novel high-performance nanocomposite based on ferrocene (Fc) functionalized graphene oxide (GO) and polyaniline (PANI) for battery-type supercapacitor applications was successfully synthesized. The GO sheets were functionalized by using 4-ferrocenylbutylamine as a redox compound. Then, the final nanocomposite was obtained by physical treatment of PANI and functionalized GO sheets. The chemical structure, electrochemical behaviors and morphological structure of synthesized compounds were confirmed by Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), galvanostatic charge-discharge measurement (GCD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis, respectively. The charge storage capacity was calculated from GCD curves. Our calculated results exhibit that the GO-Fc/PANI nanocomposite depicted high mass specific charge retention density of 208 mAh g−1 at current density 2.5 A g−1. These results indicate that the presence of Fc and PANI in the final nanocomposite improved charge transfer property of GO after modification. In addition, the GO-Fc/PANI has shown excellent cycling stability up to 3000 cycles with good retention of 85.54% of the initial charge storage capacity.

Discerning the Redox-Dependent Electronic and Interfacial Structures in Electroactive Self-Assembled Monolayers.

We explore the redox-dependent electronic and structural changes of ferrocene-terminated self-assembled monolayers (Fc SAMs) immersed in aqueous solution. By exploiting X-ray and ultraviolet photoelectron spectroscopy combined with an electrochemical cell (EC-XPS/UPS), we can electrochemically control the Fc SAMs and spectroscopically probe the induced changes with the ferrocene/ferrocenium (Fc/Fc+) redox center (Fe oxidation state), formation of 1:1 Fc+-ClO4- ion pairs, molecular orientation, and monolayer thickness. We further find the insignificant involvement of interfacial water in the Fc SAMs irrespective of redox state. Electrolyte dependencies could be identified with 0.1 M NaClO4 and HClO4 when probing partially oxidized Fc/Fc+ SAMs. Corroborating the occurrence of electrochemically induced oxidation, EC-UPS shows that oxidation to Fc+ is accompanied by a shift of the highest occupied molecular orbital toward higher binding energy. The oxidation to Fc+ is also met with an increase in work function ascribed to the induced negative interfacial dipole caused by the presence of Fc+-ClO4- ion pairs along with a contribution from the reorientation of the Fc+ SAMs. The reversibility of our observations is confirmed upon conversion from Fc+ back to the neutral Fc. The approach shown here is beneficial for a broad range of redox-responsive systems to aid in the elucidation of structure-function relationships.

Different perception of chronic constipation between patients and gastroenterologists.

There is a certain number of subjects that consider themselves to be constipated (self diagnosed constipation; SDC). The Rome Criteria separate FC from IBS-C, but some SDC patients do not meet the Rome criteria (no Rome Constipation; NRC). Our aims were to evaluate the percentage of SDC subjects with a diagnosis of FC and IBS-C and to compare demographic and clinical features, symptoms, and quality of life in the different SDC groups (FC, IBS-C, NRC). During a 2-month period, 934 patients and 980 accompanying persons (AP) were asked to complete a survey. The presence of FC or IBS-C was assessed. SDC subjects were invited to record the stool consistency (Bristol scale) and to fill in the Constipation Severity Index (CSI), obstructed defecation syndrome (ODS) and patient assessment of constipation-quality of life (PAC-QoL). The use of laxatives and enemas was evaluated. The probability of the ROME III criteria being present was higher in SDC compared with no-SDC (OR 20.5). NRC was present in 13.5% of the SDC. In the patients' group the agreement between a diagnosis of Rome III and SDC was good (K 0.62), whereas in the AP it was moderate (K 0.56). NRC showed lower mean values of ODS, CSI and PAC-QoL, higher Bristol scale and a lower use of laxatives and enemas compared to IBS-C and FC. No differences were found between IBS-C and FC. The Rome III criteria identify subjects with a greater clinical impact, but separation of FC and IBS-C does not seem justified.

Dengue virus infection-enhancement activity in neutralizing antibodies of healthy adults before dengue season as determined by using Fc\u03b3R-expressing cells

BackgroundAntibodies are critical responses to protect the host from dengue virus(DENV) infection. Antibodies target DENV by two pathologic mechanisms: virus neutralization and infection enhancement. In dengue patients, the absence of neutralizing activity in the presence of FcγR implies that infection-enhancing activity hampers the neutralizing activity of antibodies, which could potentially lead to symptomatic presentations and severe clinical outcomes.MethodsA total of 100 pair serum samples from adult healthy volunteers were obtained during the dengue season in Ha Noi in 2015 for evaluation of neutralizing and infection-enhancing activity. Additionally, 20 serum samples from acute secondary DENV infection patients were also used as the patient group in this study. PRNT was performed on BHK cells and FcγR-expressing BHK cell lines for all serum samples.ResultsOut of 100 residents, positive neutralizing antibodies (N.A) were found in 44.23 and 76.92% for DENV-1; 38.46 and 75% for DENV-2; 19.23 and 15.38% for DENV-3; and 1.92 and 9.62% for DENV-4 for pre and post-dengue season respectively. The percentage of post-exposure residents having positive responses against single, two, or more than three DENV serotypes were 38.46, 44.23 and 15.38%, respectively. A total of 34 residents were DENV seropositive before the dengue season and these individuals demonstrated further elevation of IgG antibodies after the dengue season. At the end of the season, 18 residents were confirmed to be new asymptomatic DENV infection cases. In both groups, N.A titers determined on BHK cells were higher than that on FcγR-expressing BHK cells. In heterotypic N.A responses, N.A titers to the infecting serotype from the samples obtained from pre-exposure group were significantly higher than those of the patient group. However, fold enhancement to the infecting serotypes from the samples in the pre-exposure group was substantially lower as compared to that of the patient group.ConclusionBefore and after the dengue season, serum samples from healthy volunteers demonstrated high levels of neutralizing antibodies and low or absence of infection-enhancement activity. The results suggest that while infection-enhancement activity hampers neutralizing activity of antibodies, high levels of DENV neutralizing antibodies set a critical threshold in facilitating the prevention of disease progression.

Hydrogen Production Catalyzed by Bidirectional, Biomimetic Models of the [FeFe]-Hydrogenase Active Site.

Active site mimics of [FeFe]-hydrogenase are shown to be bidirectional catalysts, producing H2 upon treatment with protons and reducing equivalents. This reactivity complements the previously reported oxidation of H2 by these same catalysts in the presence of oxidants. The complex Fe2(adtBn)(CO)3(dppv)(PFc*Et2) ([1]0; adtBn = (SCH2)2NBn, dppv = cis-1,2-bis(diphenylphosphino)ethylene, PFc*Et2 = Et2PCH2C5Me4FeCp*) reacts with excess [H(OEt2)2]BArF4 (BArF4– = B(C6H3-3,5-(CF3)2)4–) to give ∼0.5 equiv of H2 and [Fe2(adtBnH)(CO)3(dppv)(PFc*Et2)]2+ ([1H]2+). The species [1H]2+ consists of a ferrocenium ligand, an N-protonated amine, and an FeIFeI core. In the presence of additional reducing equivalents in the form of decamethylferrocene (Fc*), hydrogen evolution is catalytic, albeit slow. The related catalyst Fe2(adtBn)(CO)3(dppv)(PMe3) (3) behaves similarly in the presence of Fc*, except that in the absence of excess reducing agent it converts to the catalytically inactive μ-hydride derivative [μ-H3]+. Replacement of the adt in [1]0 with propanedithiolate (pdt) results in a catalytically inactive complex. In the course of synthesizing [FeFe]-hydrogenase mimics, new routes to ferrocenylphosphine ligands and nonamethylferrocene were developed.

Growth of maize coleoptiles in the presence of natural and synthetic growth regulators. Growth correlations

The effect of natural (IAA, FC, ABA) and synthetic (2,4-D) growth substances on the increase of the fresh weight of maize coleoptile segments and change of the pH of the incubation medium, accepted here as criteria of maize coleoptile growth, was studied. The growth of maize coleoptiles depended on the concentration of the growth substances, as well as, on the composition of the incubation medium. The highest stimulation of coleoptile growth was seen with FC at a concentration of 10&lt;sup&gt;-4&lt;/sup&gt;M, whereas ABA at 10&lt;sup&gt;-3&lt;/sup&gt; M gave the highest inhibition of maize coleoptile fresh weight increase and caused alkalization of the medium. The presence of K&lt;sup&gt;+&lt;/sup&gt; ions in the incubation medium enhanced the stimulatory effect of IAA and FC on the increase of the coleoptile fresh weight, whereas the presence of these ions and phosphate buffer abolished the growth-promoting effect of IAA and FC. The best correlation of the "fresh weight" and "pH" effects was found in the case of the growth of maize coleoptiles in the presence of FC (r&lt;sub&gt;xy&lt;/sub&gt; = 0.67). The inhibition of maize coleoptile growth in the presence of high concentrations of IAA can be explained by the destructive effect of natural auxin at these concentrations on the integrity of mitochondrial membranes, and therefore on the normal functioning of mitochondria.

Electrochemiluminescence aptasensor based on bipolar electrode for detection of adenosine in cancer cells

Here we report a novel approach for the detection of adenosine in cancer cells by electrochemiluminescence (ECL) on a wireless indium tin oxide bipolar electrode (BPE). In this approach, ferrocene (Fc) which is labeled on adenosine aptamer is enriched on one pole of the BPE by hybridization with its complementary DNA (ssDNA) and oxidized to Fc+ under an external voltage of 5.0V at the two ends of BPE. Then, a reversed external voltage was added on the BPE, making Fc+ enriched pole as cathode. The presence of Fc+ promotes the oxidation reaction on the anodic pole of the BPE, resulting in a significant increase of ECL intensity using Ru(bpy)32+/tripropylamine (TPA) system as test solution. The presence of target adenosine was reflected by the ECL signal decrease on the anodic pole caused by the target-induced removal of ferrocene-aptamer on the cathodic pole. The decrease of ECL signal was logarithmically linear with the concentration of ATP in a wide range from 1.0fM to 0.10μM. This ECL biosensing system could accurately detect the level of adenosine released from cancer cells.

Sensitive Electrochemiluminescence Biosensor Based on Au-ITO Hybrid Bipolar Electrode Amplification System for Cell Surface Protein Detection

Here we developed a novel hybrid bipolar electrode (BPE)-electrochemiluminescence (ECL) biosensor based on hybrid bipolar electrode (BPE) for the measurement of cancer cell surface protein using ferrocence (Fc) labeled aptamer as signal recognition and amplification probe. According to the electric neutrality of BPE, the cathode of U-shaped ITO BPE was electrochemically deposited by Au nanoparticles (NPs) to enhance its conductivity and surface area, decrease the overpotential of O2 reduction, which would correspondingly increase the oxidation current of Ru(bpy)3(2+)/tripropylamine (TPA) on the anode of BPE and resulting a ∼4-fold enhancement of ECL intensity. Then a signal amplification strategy was designed by introducing Fc modified aptamer on the anode surface of BPE through hybridization for detecting the amount of mucin-1 on MCF-7 cells. The presence of Fc could not only inhibit the oxidation of Ru(bpy)3(2+) because of its lower oxidation potential, its oxidation product Fc(+) could also quench the ECL of Ru(bpy)3(2+)/TPA by efficient energy-transfer from the excited-state Ru(bpy)3(2+)* to Fc(+), making the ECL intensity greatly quenched. On the basis of the cathodic Au NPs induced ECL enhancing coupled with anodic Fc induced signal quenching amplification, the approach allowed detection of mucin-1 aptamer at a concentration down to 0.5 fM and was capable of detecting a minimum of 20 MCF-7 cells. Besides, the amount of mucin-1 on MCF-7 cells was calculated to be 9041 ± 388 molecules/cell. This approach therefore shows great promise in bioanalysis.

Reagentless amperometric glucose biosensor based on the immobilization of glucose oxidase on a ferrocene@NaY zeolite composite

Ferrocene (Fc) was encapsulated in the cavities of a NaY zeolite by vapor diffusion via sublimation at below 100 °C. The resulting Fc@NaY zeolite composite was investigated by power X-ray diffraction, diffuse reflectance UV-vis and FT-IR spectroscopy, and by cyclic voltammetry. The results indicated that Fc was encapsulated into the zeolite whose microporous structure had remained intact. The Fc in the silica matrix had retained its electro- activity and did not leach out. A glucose biosensor was obtained by immobilization of the modified zeolite and glucose oxidase on a carbon paste electrode. It displays a linear response to glucose (from 0.8 μM to 4.0 mM), a detection limit of 0.2 μM, and a response time of 4 s. The good performance of the biosensor is ascribed to the biocompatibility of the zeolite and presence of Fc which facilitates the electron transfer from the enzyme to the surface of the electrode.

Abstract 755: Dendritic-cell vaccine: Cross-presentation of carcinoembryonic antigen (CEA) by dendritic cells (DCs) through a fusion protein targeting CD74 on DCs

Abstract Milatuzumab (hLL1, Immunomedics, Inc.) is a humanized anti-CD74 monoclonal IgG1 antibody (mAb) currently in phase I-II clinical trials as a therapeutic mAb for CD74-expressing non-Hodgkin lymphoma, chronic lymphocytic leukemia, and multiple myeloma. Since CD74 is also expressed by normal antigen-presenting cells (APCs), including DCs, we investigated the potential application of the Fab fragment of hLL1 as a novel targeting vector in a cancer vaccine. Methods: A fusion protein, hLL1-Fab-A3B3, was constructed by fusing the Fab fragment of milatuzumab to the A3B3 domain of CEA. The binding profiles and cytotoxic potenial of hLL1-Fab-A3B3 on APC subsets in human peripheral blood mononuclear cells (PBMCs) were assessed by flow cytometry; the impact of hLL1-Fab-A3B3 on APC function was assessed by allogeneic mixed leukocyte reaction (MLR) through CFSE-based cell proliferation assay. The cross-presentation of CEA by DCs was evaluated by three rounds of weekly stimulation of autologous T cells with DCs loaded with hLL1-Fab-A3B3 or CEA protein, followed by measuring CEA-specific CD8+ T cells with HLA-A*0201-restricted CAP-1 pentamer (YLSGANLNL). Results: Both bivalent milatuzumab and monvalent hLL1-Fab-A3B3 bound efficiently to human APC subsets, which include BDCA-1+ myeloid DCs type 1 (mDC1), BDCA-2+ plasmacytoid DCs (pDCs), BDCA-3+ myeloid DCs type 2 (mDC2), B lymphocytes, and monocytes, but neither of the two bound to T cells. While milatuzumab selectively reduced mDC1 (by 60.8%, P=0.003, n=6 donors) and mDC2 (by 53.8%, P=0.0026, n=7 donors) in PBMCs, presumably mediated by the presence of Fc, or a necessity for divalent milatuzumab binding, hLL1-Fab-A3B3 did not have this effect, nor did it affect the viability of T cells and other APC subsets (pDCs, monocytes, and B cells). The allogeneic MLR was significantly inhibited by milatuzumab (P&amp;lt;0.0001), but not by hLL1-Fab-A3B3 treatment (P=0.6644). After three rounds of weekly stimulation of autologous T cells, DCs loaded with hLL1-Fab-A3B3 were more efficient in inducing CEA-specific CD8+ T cells than DCs loaded with CEA, suggesting that the hLL1-Fab enhances the cross-presentation of CEA by DCs. Conclusion: hLL1-Fab is a promising, novel targeting antibody for use as a cancer vaccine, because it enhances the cross-presentation of antigens without significant cytotoxicity and functional alteration on APCs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 755. doi:10.1158/1538-7445.AM2011-755

Linking Antibody Fc Domain to Endostatin Significantly Improves Endostatin Half-life and Efficacy

The half-life of the antiangiogenic molecule endostatin that has been used in clinical trial is short ( approximately 2 h). In addition, approximately 50% of the clinical grade endostatin molecules lack four amino acids at their NH(2) termini. Lack of these amino acids gives rise to a molecule that is devoid of zinc, resulting in no antitumor activity. Our goal was to develop a new version of endostatin that does not show such deficiency. A recombinant human endostatin conjugated to the Fc domain of IgG was constructed and expressed in mammalian cell culture. The presence of Fc has been shown by previous investigators to play a major role in increasing the half-life of the molecule. Fc-endostatin was tested in tumor-bearing mice, and its half-life was compared with the clinical grade endostatin. The antitumor dose of Fc-endostatin was found to be approximately 100 times less than the clinical grade endostatin. The half-life of Fc-endostatin in the circulation was found to be weeks rather than hours, as observed for endostatin alone. In addition, a U-shaped curve was observed for antitumor activity of endostatin as a function of endostatin concentration delivered to the animals. Fc-endostatin is a superior molecule to the original clinical endostatin. Due to its long half-life, the amount of protein required is substantially reduced compared with the clinically tested endostatin. Furthermore, in view of the U-shaped curve of efficacy observed for endostatin, we estimate that the requirement for Fc-endostatin is approximately 700-fold less than endostatin alone. The half-life of endostatin is similar to that of vascular endothelial growth factor-Trap and Avastin, two other antiangiogenic reagents. We conclude that a new clinical trial of endostatin, incorporating Fc, may benefit cancer patients.

Induction of tumor cell death by anti-GD2 monoclonal antibodies (MoAb): Requirement of antibody Fc and a long residence time (slow koff)

13507 Background: Anti-GD2 MoAbs have shown clinical activities against neuroblastoma (NB) and other neuroectodermal tumors. Besides complement mediated (CMC) and antibody-dependent cell mediated cytotoxicities (ADCC), they can directly induce cell death. However, MoAb and their genetic constructs differ substantially in death-inducing efficiency. Although multivalent binding is important for these functions, the roles of association on rate (kon), dissociation off rate (koff), valency and Fc have not been carefully defined. Methods: We tested a panel of purified anti-GD2 MoAbs, MoAb fragment, and single chain variable fragment (scFv) fusion protein. The kinetics of in vitro binding was measured by surface plasmon resonance (SPR) using BIACORE 2000. NB cell lines (LAN1, NMB7, BE(2)C, SKNER, SKNJD and SKNLP) were treated with MoAb in vitro, their survivals were studied by the chromogenic assay and IC50 derived using Sigmaplot. Results: The most efficient cell kill against NB was 3F8 (mIgG3) with an average IC50 of 4.7 ug/ml. In contrast, IC50 was &gt;30 ug/ml for 14.G2a (mIgG2a), ME361 (mIgG2a) and S220–51 (mIgG3). It was &gt;100 ug/ml for 3F8 class-switch variant 3G6 (mIgM), 3F8-F(ab’)2(fragment), and 5F11scFv-streptavidin (tetramer). By SPR, the apparent affinity Kd (equilibrium dissociation constant) of 3F8 [1.1x10-8M] was higher than that of 3F8-F(ab’)2 [3.3x10-8M], 14.G2a [9.0x10- 8M], ME361 [4.6x10-7M], and S220–51 [4.6x10-6 M], but lower than that of decameric IgM 3G6 [6.5x10- 9 M] and tetrameric 5F11scFv-streptavidin [2.6x10-9M]. The affinity advantage of 3F8 over other bivalent MoAbs was primarily due to its slower koff [3.0x10-4 sec-1] when compared to other MoAbs [1.1x10- 3-7.3x10-2 sec-1]. Conclusions: Different structural forms of anti-GD2 MoAb have distinct efficiency in inducing NB cell death as well as binding affinity to GD2. Since these properties can affect CMC and ADCC, they may in turn influence the clinical efficacy of immunotherapy. Our findings suggest the importance of an intact IgG3 molecule (the presence of Fc), as well as a long residence time (slow koff). No significant financial relationships to disclose.

Cell-mediated fas-based lysis of dendritic cells which are apparently resistant to anti-Fas antibody.

In this report, the controversy concerning the sensitivity of dendritic cells (DCs) to Fas-dependent induction of apoptosis was examined using murine DCs. Although DCs could not be lysed when exposed to an anti-Fas antibody, Jo2, the observed resistance turned out to reflect their lack of the expression of Fc(gamma)R necessary for crosslinking the antibody, rather than their intrinsic resistance. Thus, at least a fraction of DCs was sensitive to Jo2 in the presence of Fc(gamma)R-expressing by-standers. Consistently, a significant fraction of DCs was sensitive to Fas-dependent lysis mediated by T cells including the antigen-specific killing by CD4+ T cells. Both immature (class II MHClow) and mature (class II MHChigh) DCs were sensitive to the Fas-based induction of apoptosis.

Why is the prevalence of allergic diseases increasing? A critical assessment of some classical risk factors

presence of Fc«RI-expressing LC/IDEC, bearing IgE molecules, is a prerequisite to provoking eczematous lesions, observed after application of aeroallergens to the skin of atopic patients, strongly supports this concept. Thereby, IgE receptors are the connecting link between the specificity gaining IgE molecules and the APC. However, Fc«RI seems to play the major role in these phenomena. It should be noted that Fc«RI expressed on circulating monocytes may have other functions, mainly in regulating their survival and differentiation outcome. 12 Following the presentation of allergens to T cells, allergen-specific B cells may be activated to produce high amounts of allergen-specific IgE. This IgE may then in turn bind to the Fc«RI on the APC, closing a vicious circle of facilitated antigen presentation. The intermittent or continuous supply of aeroallergens or autoantigens to the process of facilitated antigen presentation may define the pathophysiological basis of the recurrent or self-perpetuating course of AD frequently seen in untreated patients. The successful application of aeroallergens such as cat dander in the recently standardized atopy patch test 13 shows that it is possible to elicit eczematous skin lesions by solely external application of aeroallergens to the skin. Based on the facilitated antigen presentation model of AD, the need for an identification of the individual provocation factors in each patient calls for diagnostic procedures based on the allergen-specific IgE. Cat dander, house dust mite allergens and a variety of food allergens may be successfully avoided following a thoroughly undertaken prick test and in vitro IgE diagnostic evaluation.

Soluble IgA and IgG aggregates are catabolized by cultured rat mesangial cells and induce production of TNF-alpha and IL-6, and proliferation.

IgA nephropathy, a primary glomerulonephritis, is principally characterized by mesangial deposits of IgA immune complexes. Recently, it has been demonstrated that cultured glomerular mesangial cells (MC) express Fc alpha and Fc gamma receptors. In this work, we studied whether the interaction of soluble aggregates of IgA and IgG (AIgA and AIgG) with MC triggers a number of responses, including generation and release of inflammatory mediators, cell proliferation, and catabolism of the complexes. Aggregates bound to MC and were catabolized in a time-dependent manner. The percentage of cell-associated or -degraded proteins decreased in the presence of Fc, but not with Fab fragments. Both AIgA and AIgG elicited the synthesis and release of TNF-alpha and IL-6 in a dose-dependent manner, reaching a maximum between 6 and 12 h, respectively. Northern blot analysis showed that both aggregates induced the expression of mRNA encoding TNF-alpha and IL-6. Because MC proliferation is a morphologic feature commonly observed in patients with IgA nephropathy, we examined whether immune aggregates could be involved in this phenomenon. Both AIgA and AIgG induced an increase in MC number, assessed by [3H]thymidine and methylene blue uptake. The presence of anti-TNF-alpha or anti-IL-6 Abs in the medium decreased the proliferative effect triggered by aggregates. These results show that Fc alpha and Fc gamma receptor occupancy of MC induces the synthesis and release of inflammatory cytokines and proliferation, as well as the phagocytosis of stimulatory proteins. These findings could have implications for the understanding of inflammation and repair in IgA nephropathy.