Comment on "Quantum key distribution with blind polarization bases".
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Comment↗
Biomedical subjects
Xiang-Bin Wang
Publications and source records attributed to Xiang-Bin Wang.
Beating the photon-number-splitting attack in practical quantum cryptography.
We propose an efficient method to verify the upper bound of the fraction of counts caused by multiphoton pulses in practical quantum key distribution using weak coherent light, given whatever type of Eve's action. The protocol simply uses two coherent states for the signal pulses and vacuum for the decoy pulse. Our verified upper bound is sufficiently tight for quantum key distribution with a very lossy channel, in both the asymptotic and nonasymptotic case. So far our protocol is the only decoy-state protocol that works efficiently for currently existing setups.
Journal Article↗
[Biologic properties of an anti-human ovarian carcinoma/anti-human CD3 single chain bispecific antibody].
BACKGROUND & OBJECTIVE: Previous routine therapies can' t improve the survival rate of ovarian carcinoma patients. Experimental and pre-clinical data showed that bispecific antibodies could efficiently induce antitumor effect of cytotoxic cells. This study was to investigate the biologic properties of an anti-human ovarian carcinoma/anti-human CD3 single chain bispecific antibody (BHL-I) in vitro, and provide reference for pre-clinical experiment and its application. METHODS: Peripheral blood lymphocytes (PBLs), isolated from peripheral blood of healthy donors, were treated with BHL-I. The conjugation between PBLs and target ovarian carcinoma SKOV3 cells was observed under reverse microscope; the proliferation of peripheral blood mononuclear cells (PBMCs) and cytotoxicity of PBLs to SKOV3 cells were detected by MTT assay; the concentrations of human interferon-gamma (hIFN-gamma) and human tumor necrosis factor-alpha (hTNF-alpha), secreted by PBLs in the process of killing target cells, were detected by ELISA. RESULTS: The rosette (PBL-SKOV3) formation rate was significantly higher in BHL-I group than in control group (15.7% vs. 11.1%, P<0.01). BHL-I significantly enhanced the proliferation of PBLs and cytotoxicity of PBLs to SKOV3 cells in the presence of relative antigen (P<0.01); the cytotoxic rate was positively correlated with the rosette formation rate (r=0.946); the concentrations of hIFN-gamma and hTNF-alpha were significantly increased (P<0.01). CONCLUSION: BHL-I could mediate conjugation between PBLs and SKOV3 cells, and activate the cytotoxicity of PBLs which may relate with up-regulation of hIFN-gamma and hTNF-alpha.
Antibodies, Bispecific↗
Quantum key distribution with two-qubit quantum codes.
We propose a prepare-and-measure scheme for quantum key distribution with two-qubit quantum codes. The protocol is unconditionally secure under all types of intercept-and-resend attack. Given the symmetric and independent errors to the transmitted qubits, our scheme can tolerate a bit of an error rate up to 26% in four-state protocol and 30% in six-state protocol, respectively. These values are higher than all currently known threshold values for the prepare-and-measure protocols. Moreover, we give a practically implementable linear optics realization for our scheme.
Journal Article↗
A new recombinant single chain trispecific antibody recruits T lymphocytes to kill CEA (carcinoma embryonic antigen) positive tumor cells in vitro efficiently.
Anti-tumor associated antigen (TAA).CD3.CD28 trispecific antibody(TsAb) is able to provide two signals for fully and continuously activation of T lymphocytes and recruit them around tumor cells, presenting an attractive concept in tumor immunotherapy. Here, a new single chain trispecific antibody (scTsAb), named CEA-scTsAb, was constructed by fusion of anti-CEA (Carcinoma Embryonic Antigen) single chain antibody (scFv), anti-CD3 scFv and anti-CD28 VH, spaced by polypeptide interlinkers taken from the fragment of constant region (FC) of human IgG and human serum albumin (HSA). It was expressed in Escherichia coli at low temperature (30 degrees C) with up to 50% of the antibody being present in soluble form. After one step of DEAE anion chromatography, the soluble product was sufficiently pure for further in vitro activity assays. First, it was proved that CEA-scTsAb could recognize three antigens (CEA, CD28 and Jurkat cell membrane antigen) specifically and could distinguish antigen positive cells from antigen negative cells in vitro. Then fresh PBMC (peripheral blood mononuclear cells), without being pre-treated by co-stimulatory reagents, such as IL-2 or CD28 mAb, were used as effector cells to test their ability to mediate tumor specific cytolysis of CEA-positive tumor cells, SW1116. It was found by photomicrography that T lymphocytes were attracted to SW1116 cells in the presence of CEA-scTsAb, which resulted in effective cytolysis of tumor cells. As shown by MTT assay, the efficacy of tumor specific cytolysis mediated by CEA-scTsAb related to both the quantity and activation of PBMC. At an effector cells/target cells ratio (E/T) of 5, it was proved by dual-color FACS with propidium iodide (PI) and FITC-annexin V that both necrosis and apoptosis of tumor cells were causes of tumor specific cytolysis. In summary, a new single chain trispecific (CEA x CD3 x CD28) antibody was constructed and characterized carefully in this paper and was found to possess functions: (i) to activate T lymphocytes independently of additional co-stimulatory signal, (ii) to attract activated T lymphocytes around CEA-positive tumor cells, (iii) to attack CEA-positive tumor cells with recruited T lymphocytes. Because it recognizes a widely distributed tumor antigen (CEA), with moderate molecular weight (about 75 kDa) and a simple production procedure, and is able to mediate a high level of tumor specific cytolysis without any additional co-stimulating reagents, CEA-scTsAb is very promising for the task of immunotherapy in future.
Antibodies, Monoclonal↗
A new approach for rapidly reshaping single-chain antibody in vitro by combining DNA shuffling with ribosome display.
Antibody reshaping is an effective way to reduce the immunogenicity while maintaining or improving the affinity of murine antibodies. This paper describe a new in vitro approach for rapidly reshaping murine antibodies by combining DNA shuffling with ribosome display. With the new method, a reshaping anti-4-1BB single-chain antibody (scFv), Re-4B4-1 scFv, which bound to its antigen (4-1BB) specifically and strongly, was selected from a reshaping library. These results proved definitely the feasibility of the new designed approach for antibody reshaping.
Amino Acid Sequence↗
Soluble expression of recombinant human secondary lymphoid chemokine (SLC) in E. coli and research on its in vitro and in vivo bioactivity.
Secondary lymphoid tissue chemokine (SLC) is a CC chemokine that plays an important role in leukocytes homing to lymphoid tissues. The ability of SLC to co-localize both T cells and dendritic cells formed the rationale to evaluate its utility in cancer immunotherapy. The in vivo antitumor effect of murine SLC (mSLC) has been well documented, but little is known about that of human SLC (hSLC). To investigate the antitumor efficiency in vivo of hSLC, the hSLC gene was artificially synthesized and induced to express as a soluble form in Escherichia coli. After purification, the purity of the recombinant human SLC (rhSLC) protein was above 95% by SDS-PAGE analysis. The K(d) of rhSLC binding to peripheral blood lymphocytes (PBLs) was 0.2186 +/- 0.02675 microM as assessed by FACS, and the maximal chemotactic index of rhSLC was 9.49 at 100 nM as assessed by in vitro chemotaxis assay. Then genomic sequences of hSLC and mSLC, and of human CCR7 (hCCR7) and murine CCR7 (mCCR7), the receptor for SLC, were aligned. It was found that hSLC and mSLC share 70.72% identity and hCCR7 and mCCR7share 86.77% identity. Furthermore, we found that rhSLC could chemoattract murine peripheral blood mononuclear cells (PBMCs) in vitro. On the basis of these facts, immune competent mice inoculated with S180 sarcoma cells were chosen as an in vivo model. Intratumoral injections of rhSLC inhibited tumor growth and increased survival. These findings suggest that, despite its incapability to bind to either human or murine CXCR3, which is related to angiostasis, rhSLC can induce an antitumor response in vivo by another route. This report proves that rhSLC has a potent tumor-inhibition ability that makes it a promising candidate agent in cancer immunotherapy.
Adult↗
A new model of trispecific antibody resulting the cytotoxicity directed against tumor cells.
Bispecific antibodies (BsAb) with specificity to both tumor cells and CD3 molecule were believed to be promising immunological tools for the therapy with minimal residual diseases by activating cytotoxic T cells. However, without costimulatory molecule CD28, the activated T cells tended to apoptosis. In order to kill tumor cells more efficiently, a recombinant multifunctional single-chain trispecific antibody (scTsAb), which contains anti-ovarian carcinoma (OC) scFv, anti-CD3 scFv and VH domain of anti-CD28 antibody, was constructed and expressed in E. coli BL21 Star strain. The scTsAb showed strong binding avidities to membrane antigen of SK-OV-3 cell, CD3 molecule on Jurkat cell, and recombinant CD28 antigen. It was further demonstrated that this scTsAb could activate peripheral blood T cells to elicit strong cytotoxicity against SK-OV-3 cells. This new type of recombinant scFv antibody set up a new technological platform for T cells based immunotherapy against cancer, especially with the failure on MHC antigen presentation or absence of costimulating signal.
Antibodies, Bispecific↗
[An efficient approach to the synthesis of a high-quality random peptide repertoire].
During the construction of a random peptide repertoire using degenerate models, unexpected amino acids or stop codons are almost unavoidable. To conquer this shortcoming, a new split-mix-split method of oligonucleotide synthesis was developed. A 13-amino acids random peptide library had been constructed by using this method. The sequencing results of 16 clones indicated that neither stop codon nor codon for cysteine appeared as designed. The occurrence rations of 19 amino acids were also calculated and no obvious amino acid bias had been observed. By using this method, the type and quantity of amino acid at certain position of a peptide could be controlled well, so this split-mix-split method, combined with degenerate could meet the needs of a high diversity random peptide library.
Amino Acid Sequence↗
A method for constructing reshaping single-domain antibody.
The aim of this research was to demonstrate a novel and practical method for constructing reshaping Single-domain antibodies. Different from other methods, our method does not need to model the configuration of antibodies with specific sequences to determine the sequences of human acceptor FRs and then determine which amino acid residues in human acceptor FRs should be substituted. Most importantly, reshaping and enhancing the antigen binding affinity shared one procedure at the same time. Using this method, the reshaping anti-CD28 single-domain antibodies were constructed. According to the amino acid sequence of a mouse anti-human CD28 monoclonal antibody VH, two most homologous sequences of human antibodies were selected from GenBank and one of them was used as a main framework region for constructing the reshaping antibody. Before the original mouse antibody CDRs were inserted into the human acceptor FRs, some amino acid residues which were different from those of the original mouse antibody in the corresponding positions of the human acceptor FRs were determined or alternatively mutated by their conservative properties in Kabat classification. When the synthesized nucleotide fragments in different length were spliced by overlap PCR into the entire reshaping genes, Taq DNA polymerase and high Mg2+ concentration were used to introduce more mutation in FRs and CDRs randomly. A phage library was constructed using these PCR products and several reshaping Single-domain antibodies with high antigen binding affinity were selected after three rounds of panning. Two of them were expressed in E. coli BL21 (DE3). The antigen-binding affinity of refolded proteins was still in a high level measured by ELISA. These results suggested that this method was feasible and efficient for constructing reshaping Single-domain antibodies.
Amino Acid Sequence↗