Interaction Of CD2 Research Articles

Cis interactions between CD2 and its ligands on T cells are required for T cell activation.

CD2 is largely described to promote T cell activation when engaged by its ligands, CD48 in mice and CD58 in humans, that are present on antigen-presenting cells (APCs). However, both CD48 and CD58 are also expressed on T cells. By generating new knockout mouse strains lacking CD2 or CD48 in the C57BL/6 background, we determined that whereas CD2 was necessary on T cells for T cell activation, its ligand CD48 was not required on APCs. Rather, CD48 was also needed on T cells. One exception was during cytotoxicity, which required CD48 on T cells and APCs. Fluorescence resonance energy transfer (FRET) studies in nonimmune cells provided evidence that cis interactions between CD2 and CD48 existed within individual cells. CD2-CD48 interactions on T cells enabled more robust T cell receptor (TCR) signals, including protein tyrosine phosphorylation. Using T cells from a CD2 knock-in mouse in which a tag was inserted at the carboxyl terminus of CD2, mass spectrometry analyses revealed that the role of CD2 in T cell activation correlated with its ability to interact with components of the TCR complex and the protein tyrosine kinase Lck. CD2-CD58 provided a similar function in human T cells. Thus, our data imply that T cell-intrinsic cis interactions of CD2 with its ligands are required for TCR signaling and T cell activation. Interactions with ligands on APCs contribute during cytotoxicity.

DFT insight into Cd2+, Hg2+, Pb2+, Sn2+, As3+, Sb3+, and Cr3+ heavy metal ions adsorption onto surface of bowl-like B30 nanosheet

Contamination of water resources by heavymetal ions, is a drastic environmental concern. In this study, the interaction of Cd2+, Hg2+, Pb2+, Sn2+, As3+, Sb3+, and Cr3+ metal ions onto surface of the bowl-like B30 nanosheet was scrutinized based on density functional theory (DFT) calculations. Adsorption energy (Eads) values revealed that the As3+ interacted better with bowl-like B30 nanosheet in comparison to other metal ions, having adsorption energy values of −299.57 and −628.56 kcal mol−1in the gas phase and aqueous media, respectively. However, Hg2+, Pb2+, and Sn2+ metal ions physically adsorbed onto bowl-like B30 nanosheet in the gas phase because of their much less value of adsorption energy. The sign of adsorptionGibbs free energy change(ΔGads) and adsorption enthalpy change (ΔHads) values for all complexes was found to be negative in the gas phase and aqueous media, which indicated that the adsorption process is spontaneous and exothermic. Frontier molecular orbital (FMO) analysis exhibited a decrease in the HOMO-LUMO energy gap of studied complexes, boosting the electrical conductivity of these complexes. Natural bond orbital (NBO) analysis and charge decomposition analysis (CDA) revealed donor–acceptor charge transfer interactions in the complexes. The UV–vis results depicted that λmax was red-shifted during interactions of meal ions with bowl-like B30 nanosheet. Finally,quantum theoryof atoms in molecules (QTAIM) exhibited that the interaction between As3+ metal ion and the nanosheet is covalent in nature, while the other metal ions have predominantly electrostatic with partially covalent and non-covalent characters. The theoretical results of the study represented the feasibility of applying bowl-like B30 nanosheet to remove heavy metal ions, especially As3+ and providing information for experimental researchers to treat wastewaters.

Probing the Interaction of Heavy and Transition Metal Ions with Silver Nanoparticles Decorated on Graphene Quantum Dots by Spectroscopic and Microscopic Methods.

We report a comprehensive study of the interaction of transition and heavy metal ions with graphene quantum dots-capped silver nanoparticles (AgGQDs) using different spectroscopic and microscopic techniques. High-resolution transmission electron microscopy studies show that the interaction of metal ions with AgGQDs leads to the formation of metal oxides, the formation of zerovalent metals, and the aggregation of Ag nanoparticles (AgNPs). The metal ions may interact with AgGQDs through selective coordination with -OH and -COOH functionalities, adsorption on the graphene moiety, and directly to AgNPs. For instance, the interaction of Cd2+ with AgGQDs altered the spherical shape of AgNPs into a chain-like structure. On the contrary, the formation of PbO is observed after the addition of Pb2+ to AgGQDs. Interestingly, the interaction of AgGQDs with Hg2+ results in the complete dissolution of Ag0 from the surface of GQDs and subsequent deposition of Hg0 on the graphene moiety of GQDs. Unlike transition metal ions, Cd2+, Pb2+, and Hg2+ can adsorb strongly on the graphene surface at the bridge, hollow, and top sites, respectively. This special interaction of heavy metal ions with the graphene surface would decide the mechanistic pathway in which the reaction proceeds. The transition metal ions Cu2+, Zn2+, Co3+, Mn2+, Ni2+, and Fe3+ induced the aggregation of AgNPs.

Interactions of Cd2+, Co2+ and MoO42− Ions with Crushed Concrete Fines

Construction and demolition activities generate approximately two thirds of the world’s waste, with concrete-based demolition material accounting for the largest proportion. Primary aggregates are recovered and reused, although the cement-rich fine fraction is underutilised. In this study, single metal batch sorption experiments confirmed that crushed concrete fines (CCF) are an effective sorbent for the maximum exclusion of 45.2 mg g−1 Cd2+, 38.4 mg g−1 Co2+ and 56.0 mg g−1 MoO42− ions from aqueous media. The principal mechanisms of sorption were determined, by scanning electron microscopy of the metal-laden CCF, to be co-precipitation with Ca2+ ions released from the cement to form solubility limiting phases. The removal of Co2+ and MoO42− ions followed a zero-order reaction and that of Cd2+ was best described by a pseudo-second-order model. The Langmuir model provided the most appropriate description of the steady state immobilisation of Cd2+ and Co2+, whereas the removal of MoO42− conformed to the Freundlich isotherm. Long equilibration times (>120 h), loose floc formation and high pH are likely to limit the use of CCF in many conventional wastewater treatment applications; although, these properties could be usefully exploited in reactive barriers for the management of contaminated soils, sediments and groundwater.

Effect of temperature during the synthesis process of CdSe nanoparticles using the colloidal technique

AbstractIn this work, the first results of the effects of temperature during the production of Se2- ions and the effect during the interaction of Cd2+ and Se2- ions in the synthesis process of CdSe nanoparticles are presented. The synthesis of CdSe was carried out by the colloidal technique, in the first one we used a temperature of 63 °C to produce Se2- ions and in the second one an interaction temperature of 49 °C. The samples were characterized using a Scanning Electron Microscope (SEM) and a Scanning Tunneling Microscope (STM). From the SEM micrographs it was possible to identify the thorns formation and irregular islands. STM micrographs reveal elliptical shapes with a regular electron cloud profile.

Rosetting T cells in Hodgkin lymphoma are activated by immunological synapse components HLA class II and CD58

AbstractA unique feature of Hodgkin lymphoma (HL) is the presence of CD4+ T cells that surround, protect, and promote survival of tumor cells. The adhesion molecules involved in this so-called T-cell rosetting are important components of the immunological synapse (IS). However, it is unknown whether this synapse is fully assembled and leads to T-cell activation by enabling interaction between the T-cell receptor (TCR) and human leukocyte antigen class II (HLA-II). We established a novel rosetting model by coculturing HLA-II–matched peripheral blood mononuclear cells with HL cell lines and showed IS formation with activation of rosetting T cells. HLA-II downregulation by class II transactivator knockout did not affect the extent of rosetting, but almost completely abrogated T-cell activation. Intriguingly, the level of CD58 expression correlated with the extent of rosette formation, and CD58 knockout or CD2 blockade reduced both rosette formation and T-cell activation. The extension of our findings to primary HL tissue by immunohistochemistry and proximity ligation assays showed interaction of CD2 with CD58 and of TCR-associated CD4 with HLA-II. In conclusion, T-cell rosetting in HL is established by formation of the IS, and activation of rosetting T cells critically depends on the interaction of both TCR-HLA-II and CD2-CD58.

Modulation of co-stimulatory signal from CD2-CD58 proteins by a grafted peptide.

Peptides were designed to inhibit the protein-protein interaction of CD2 and CD58 to modulate the immune response. This work involved the design and synthesis of eight different peptides by replacing each amino acid residue in peptide 6 with alanine as well as grafting the peptide to the sunflower trypsin-inhibitor framework. From the alanine scanning studies, mutation at position 2 of the peptide was shown to result in increased potency to inhibit cell adhesion interactions. The most potent peptide from the alanine scanning was further studied for its detailed three-dimensional structure and binding to CD58 protein using surface plasmon resonance and flow cytometry. This peptide was used to graft to the sunflower trypsin inhibitor to improve the stability of the peptide. The grafted peptide, SFTI-a1, was further studied for its potency as well as its thermal, chemical, and enzymatic stability. The grafted peptide exhibited improved activity compared to our previously grafted peptide and was stable against thermal and enzymatic degradation.

Two plant growth promoting bacterial Bacillus strains possess different mechanisms in adsorption and resistance to cadmium

Microorganisms are promising biosorbents for decontaminating cadmium-polluted soil or water systems, but the underlying remediation mechanisms are still unclear. In this study, the cadmium biosorption mechanisms and capabilities of plant growth-promoting microorganisms (Bacillus megaterium NCT-2 and Bacillus paranthracis NT1) were investigated. Batch biosorption experiments showed that the optimal biosorption conditions for B. megaterium NCT-2 and B. paranthracis NT1 were pH 6.0, a biomass dosage of 1.0 g L−1, and an initial Cd2+ concentration of 10 mg L−1, and pH 8.0, a biomass dosage of 1.0 g L−1, and an initial Cd2+ concentration of 10 mg L−1, respectively. The biosorption processes of both biosorbents were well described by the pseudo-second order kinetic model, which indicated that the biosorption of Cd2+ was mainly chemisorption. The intracellular accumulation portion of adsorbed Cd2+ in B. megaterium NCT-2 was much higher than in B. paranthracis NT1 (43.11% and 3.25%, respectively), which resulted in the lower cadmium tolerance (14 mg L−1 and 280 mg L−1, respectively) and higher cadmium removal efficiency (46.79% and 20.45%, respectively) of B. megaterium NCT-2 compared to B. paranthracis NT1. SEM-EDS and FTIR analysis suggested the probable interactions of Cd2+ with the biosorbent surface ligands, such as -OH, -NH, -SO3, CO and -COOH during surface adsorption. Results of qRT-PCR illustrated that the difference in cadmium resistant mechanism and adsorption performance between B. megaterium NCT-2 and B. paranthracis NT1 may be regulated by the genes cadA, zitB, khtT, and bshA and cadA, trkA, czcD, and bshA, respectively. Our results revealed that these two biosorbents have the potential for further use in the development of cadmium remediation technologies and could provide insight into the mechanisms of cadmium biosorption.

Effects of calcium application on the yields of flavonoids and saponins in Panax notoginseng under cadmium stress

ABSTRACT Under different concentrations of cadmium treatments (Cd2+ concentration: 0, 0.6, 6.0, 12.0 mg/kg, prepared with CdCl2•2.5H2O), pot experiments were conducted to study the application of two calcium-containing substances (Ca2+ concentration: 0, 180, 360 mg/kg, prepared with calcium chloride CaCl2 and lime Ca(OH)2) on the yields of flavonoids and saponins of P. notoginseng. The results showed that the application of calcium chloride and lime could increase the biomass of the main root of P. notoginseng and significantly reduce the cadmium contents. Under 0 and 0.6 mg/kg cadmium treatment, the cadmium content in the main root of P. notoginseng did not exceed the standard value (Cd≤0.5 mg/kg1, GB/T 19086–2008). Under 0.6 mg/kg cadmium treatment, the application of calcium chloride increased the yield of flavonoids in the main root of P. notoginseng. The yield of flavonoids in the main root of P. notoginseng decreased under the treatment of 360 mg/kg Ca2+ lime and 0.6 mg/kg Cd2+. Under the treatments of 6.0 mg/kg and 12.0 mg/kg cadmium stress, calcium chloride and lime reduced the yield of flavonoids in P. notoginseng by 14.2%-35.2%. There was a significant positive logarithmic function correlation between flavonoid yield and ratio of Ca/Cd treatment concentration (P < 0.05). Under the treatment of 0.6 mg/kg Cd2+ with 180 mg/kg Ca2+ (calcium chloride), yields of Rg1, Rb1 and total saponins of P. notoginseng reached the highest and were increased by 114.9%, 323.0% and 172.4%, respectively, compared with no calcium chloride treatment. Under different Cd treatment levels and lime application, the yields of Rg1, Rb1 and total saponins of P. notoginseng decreased and the yield of R1 remained relatively stable. Under a certain concentration of cadmium treatment, appropriate calcium chloride and lime application could increase or maintain the biomass, saponin and flavonoid yields of the main root of P. notoginseng. Yields of R1, Rg1, Rb1 and SPN were influenced due to interaction of Cd2+ and Ca2+. In order to ensure the cadmium content of P. notoginseng less than the standard value and optimal yields of flavonoids and saponins, it could be recommended to apply calcium chloride or lime 1125 kg/hm (180 mg/kg Ca2+) under 0.6 mg/kg Cd2+ treatment.

A pH‐Dependent Colorimetric Probe Based on Sodium Dodecyl Sulfate Silver Nanoparticles for Cadmium(II) and Aluminum(III) Determination

AbstractA novel pH‐dependent sensitive and convenient assay was proposed for the determination of Cd2+ and Al3+ in aqueous medium using the sodium dodecyl sulfate (SDS) modified AgNPs as signal probes. In different pH values, the probe showed a visually detectable color change based on the strong interaction of Cd2+ and Al3+ with SDS. The color of SDS‐AgNPs solution would change from bright yellow to purple red in the presence of Cd2+ at pH 9.8, and to reddish brown in the presence of Al3+ at pH 5.5. Under the optimum experimental conditions, the ratio of A580 nm/A390 nm of SDS‐AgNPs gradually increased with increasing of Cd2+, and a good linear relationship was achieved when Cd2+ concentration ranging from 4.2×10−8 M to 3.0×10−6 M. Linear decreasing of A390 nm related to Al3+ concentration was over the range of 3.6×10−8 M to 2.0×10−6 M. The limit of detection was as low as 11.2 nM Cd2+ and 7.2 nM Al3+, respectively. Importantly, it has been successfully applied to detect Cd2+ and Al3+ in real samples.

Effects of chlorogenic acid on the binding process of cadmium with bovine serum albumin: A multi-spectroscopic and docking study

Chlorogenic acid (CGA), a natural phenolic product, plays an increasingly positive role in removing the toxicity of heavy metals owing to its antioxidative activity and metal-chelating properties. Cadmium (Cd), as a ubiquity heavy metal, can enter the human body and increase health risk. In this study, we investigated the effects of CGA on conformational changes of Cd2+-induced bovine serum albumin (BSA) by multiple spectroscopic methods, including ultraviolet–visible (UV–vis), fluorescence and circular dichroism spectroscopy (CD), as well as molecular docking. The result of the fluorescence spectroscopy revealed that the binding constant of (Cd2+-CGA)-BSA was smaller than that of Cd2+-BSA at 298 K (6.34 × 102 L/mol vs 22.7 × 102 L/mol). UV–vis spectroscopy described that the CGA could reduce the changes on the main chain structure of BSA induced by the high concentrations Cd2+ (8 and 16 × 10−4 mol/L). CD results showed an increase in α-helix content from 60% in Cd2+-BSA to 70% in (Cd2+-CGA)-BSA interaction, whereas β-sheet content decreased from 7% to 4%, the random coil content decreased from 33% to 26%, which indicating that the chelation of CGA with Cd2+ reduced the unfolding in the protein peptide chain and enhanced the hydrophobicity of BSA induced by Cd2+ alone. The data of Forsters resonance energy transfer proved that CGA reduced the structural changes of BSA by shortening the distance between Cd2+ and BSA. The computational techniques indicated that CGA might reduce the interaction of Cd2+ with BSA by forming hydrogen bonds with Cd2+. The findings in our study will provide a useful reference for exploring the effect of CGA on Cd2+-induced changes in albumin function.

Wien effect of Cd/Zn on soil clay fraction and their interaction

BackgroundThe coexistence of Cd2+ and Zn2+ ions in nature has a significant influence on their environmental behaviors in soils and bioavailability for plants. While many studies have been done on the mutual toxicity of Cd2+ and Zn2+, few studies can be found in the literature focused on the interaction of Cd2+ and Zn2+ on soil clay fractions especially in terms of energy relationship.ResultsThe binding energies of Cd2+ on boggy soil (Histosols) particles and Zn2+ on yellow brown soil (Haplic Luvisols) particles were the highest, while those of Cd2+ and Zn2+ on paddy soil (Inceptisols) particles were the lowest. These results indicated that Cd2+ and Zn2+ have a strong capacity to adsorb in the solid phase at the soil–water interface of boggy soil and yellow brown soil, respectively. However, both Cd2+ and Zn2+ adsorbed on paddy soil particles easily release into the solution of the soil suspension. Unlike the binding energy, the higher adsorption energies of ions in boggy and yellow brown soils showed a weak binding force of ions in boggy soil and yellow brown soil. A 1:1 ratio of Cd2+ to Zn2+ promotes the mutual inhibition of their retentions. Cd2+ and Zn2+ have high mobility and bioavailability in paddy soil and yellow drab soil (Ustalfs), whereas they have high potential mobility and bioavailability in boggy soil and yellow brown soil.ConclusionIn the combined system, Zn2+ had preferential adsorption than Cd2+ on soil clay fractions. Boggy soil and yellow brown soil have a low environmental risk with lower mobility and bioavailability of Cd2+ and Zn2+ while paddy soil and yellow drab soil present a substantial environmental risk. In the combined system, Cd2+ and Zn2+ restrain each other, resulting in the weaker binding force between ions and soil particles at a 1:1 ratio of Cd2+–Zn2+.

Design of an electrochemical DNA-based biosensor for selective determination of cadmium ions using a DNA hybridization indicator

A simple electrochemical DNA- based biosensor was designed for determination of Cd2+ using ethyl green (EG) as a DNA hybridization indicator on the surface of carbon paste electrode (CPE). The interaction of Cd2+ with double strand DNA (dsDNA) led to the destabilizing of dsDNA and the increase in the reduction peak currents of EG. The difference in the values of electrochemical responses of EG before and after DNA helix destabilization in the presence of Cd2+ (ΔI) was used for Cd2+ determination and was linearly related to the concentration of Cd2+ over the ranges of 1.0pM–1.0nM and 10.0nM–1.0μM. Detection limit was achieved as low as 0.3pM using simple and low cost working electrode and without applying any materials for modification of electrode or DNA. The proposed biosensor was utilized successfully to real sample analysis of Cd2+.

Nurse-like cells promote CLL survival through LFA-3/CD2 interactions.

In the tumoral micro-environment (TME) of chronic lymphocytic leukemia (CLL), nurse-like cells (NLC) are tumor-associated macrophages which play a critical role in the survival and chemoresistance of tumoral cells. This pro-survival activity is known to involve soluble factors, but few data are available on the relative role of cells cross-talk. Here, we used a transcriptome-based approach to systematically investigate the expression of various receptor/ligand pairs at the surface of NLC/CLL cells. Their relative contribution to CLL survival was assessed both by fluorescent microscopy to identify cellular interactions and by the use of functional tests to measure the impact of uncoupling these pairs with blocking monoclonal antibodies. We found for the first time that lymphocyte function-associated antigen 3 (LFA-3), expressed in CLL at significantly higher levels than in healthy donor B-cells, and CD2 expressed on NLC, were both key for the specific pro-survival signals delivered by NLC. Moreover, we found that NLC/CLL interactions induced the shedding of soluble LFA-3. Importantly, in an exploratory cohort of 60 CLL patients receiving frontline immunochemotherapy, increased levels of soluble LFA-3 were found to correlate with shorter overall survival. Altogether, these data suggest that LFA-3/CD2 interactions promote the survival of CLL cells in the tumor microenvironment.

Synthesis and Structural Characterization of Cadmium(II) and Mercury(II) Complexes Derived from 3‐Aminoquinoline

AbstractTwo novel metal complexes derived from interactions of Cd2+ and Hg2+ ions with 3‐aminoquinoline in the molar ratio 1 : 2 are reported. The synthesized and isolated metal complexes were characterized by UV/VIS, FT‐IR, 1H‐ and 13C‐NMR, and ESI‐MS spectroscopic studies, and elemental analyses. FT‐IR and NMR studies confirmed that the NH2 group remains uncoordinated in both synthesized complexes. The molecular structure of the CdII complex was additionally determined by X‐ray single‐crystal analysis. The Cd complex crystallizes in the triclinic centrosymmetric P$\bar 1$ space group. Moreover, the CdII complex exists as neutral discrete molecule and was found to show tetrahedral geometry.

Facile Synthesis of Galactosamine‐Stabilized Gold Nanoparticles with Sensitive Cd2+ Sensing

AbstractCadmium is one of the most toxic and dangerous heavy‐metal elements to human health and environmental safety. Therefore, it is very useful to develop simple, rapid, and sensitive methods for the detection of Cd2+ ions in real samples. Here, we report the simple synthesis of galactosamine‐functionalized gold nanoparticles (Galn‐GNPs) at room temperature. The Galn‐GNPs can be used as a colorimetric probe for the detection of Cd2+ ions through localized surface plasmon resonance. A linear response to the concentration of Cd2+ ions was observed in the range 1 to 100 nM. The detection limit is as low as 3 nM, which is below the maximum recommended contamination level of the World Health Organization for cadmium in drinking water of 3 ppb (15 nM). The specific interactions of Cd2+ ions with Galn‐GNPs provided excellent selectivity for the detection of Cd2+ ions over 15 other metal ions (Pb2+, Mg2+, Zn2+, Ni2+, Cu2+, Co2+, Ca2+, Mn2+, Cr3+, Ba2+, Cr6+, Ag+, Fe3+, Al3+, and Hg2+). The selectivity of this system toward Cd2+ ions was remarkably fivefold higher than that for other metal ions. The aggregation‐based change in color from red to purple occurred in less than 20 s. This method is simple and fast and has also been successfully applied to the detection of Cd2+ ions in lake‐water samples.

Role of Defects in Carbon Nanotube Walls in Deposition of CdS Nanoparticles from a Chemical Bath

Multiwall carbon nanotubes (MWCNTs), as-prepared and annealed in an inert atmosphere, have been used as templates for growth of CdS nanoparticles from an aqueous ammonium solution of cadmium chloride and thiourea. Transmission electron microscopy and Raman spectroscopy revealed that formation of CdS nanocrystals on the raw MWCNT surface proceeds markedly faster than on the annealed one. X-ray photoelectron spectroscopy showed a strong difference in the chemical state of the deposited CdS depending on the defect density in the MWCNTs. An interaction of Cd2+ ions and mixed Cd(II) complexes with a defective graphene fragment was studied using density functional theory. The calculations indicated that, for attachment of Cd-containing species to the graphitic surface, defects with the dangling carbon bonds are needed. By combining the experimental and theoretical results, a model of CdS nucleation on the MWCNTs was proposed.

Role of extracellular polymeric substances from Chlorella vulgaris in the removal of ammonium and orthophosphate under the stress of cadmium

The interactions between the soluble extracellular polymeric substances (S-EPS), bound EPS (B-EPS) of algae and heavy metal, would affect the removal of ammonium (NH4+-N) and orthophosphate (PO43−-P) from wastewater by algae-based techniques. This study investigated the role of Cd2+-mediated EPS from Chlorella vulgaris on NH4+-N and PO43−-P removal. The results showed that the removal efficiencies of NH4+-N and PO43−-P still separately remained 62.6% and 64.9% under 1.0mg/L Cd2+, compared to those without Cd2+, mainly attributing to enhanced S-EPS and B-EPS contents of the algae. The increased of PS (polysaccharides) and PN (proteins, e.g., tryptophan-like and tyrosine-like components) led to accelerated interactions of Cd2+ with PS and PN in EPS fractions, especially for B-EPS, due to a higher detected distribution of Cd2+ (e.g., about 55.4% in B-EPS). Thus, algae-based techniques are stable treatment methods for wastewater in which NH4+-N and PO43−-P coexist with heavy metals.

Application of photocatalytic cadmium sulfide nanoparticles to detection of enzymatic activities of glucose oxidase and glutathione reductase using oxidation of 3,3′,5,5′-tetramethylbenzidine

It was found out that semiconductor CdS nanoparticles (NPs) are able to catalyze photooxidation of the well known chromogenic enzymatic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by oxygen. The photocatalytical oxidation of TMB does not require hydrogen peroxide and its rate is directly proportional to the quantity of CdS NPs produced in situ through the interaction of Cd2+ and S2− ions in an aqueous medium. This phenomenon was applied to development of colorimetric sensitive assays for glucose oxidase and glutathione reductase based on enzymatic generation of CdS NPs acting as light-powered catalysts. Sensitivity of the developed chromogenic assays was of the same order of magnitude or even better than that of relevant fluorogenic assays. The present approach opens the possibility for the design of simple and sensitive colorimetric assays for a number of enzymes using inexpensive and available TMB as a universal chromogenic compound.

Alefacept Promotes Immunosuppression-Free Renal Allograft Survival in Nonhuman Primates via Depletion of Recipient Memory T Cells

Renal allograft tolerance has been achieved in MHC-mismatched primates via nonmyeloablative conditioning beginning 6 days prior to planned kidney and donor bone marrow transplantation (DBMT). To extend the applicability of this approach to deceased donor transplantation, we recently developed a novel-conditioning regimen, the “delayed protocol” in which donor bone marrow (DBM) is transplanted several months after kidney transplantation. However, activation/expansion of donor-reactive CD8+ memory T cells (TMEM) occurring during the interval between kidney and DBM transplantation impaired tolerance induction using this strategy. In the current study, we tested whether, Alefacept, a fusion protein which targets LFA-3/CD2 interactions and selectively depletes CD2highCD8+ effector memory T cells (TEM) could similarly induce long-term immunosuppression-free renal allograft survival but avoid the deleterious effects of anti-CD8 mAb treatment. We found that Alefacept significantly delayed the expansion of CD2high cells including CD8+ TEM while sparing naïve CD8+ T and NK cells and achieved mixed chimerism and long-term immunosuppression-free renal allograft survival. In conclusion, elimination of CD2high T cells represents a promising approach to prevent electively the expansion/activation of donor-reactive TEM and promotes tolerance induction via the delayed protocol mixed chimerism approach.