We present a bispecific antibody that recognizes an antigen and a hapten and can be applied to various biological assays, including immunoblotting and immunoprecipitation. In immunoblot analysis of serum, an anti-C5 x anti-cotinine bispecific tandem single-chain variable fragment (scFv)-Fc fusion protein and cotinine-conjugated horseradish peroxidase (HRP) generated a clean signal without the high background that was observed in a parallel experiment using HRP-conjugated goat anti-rabbit immunoglobulin G (Fc-specific) antibody. In immunoprecipitation analysis of serum, use of the bispecific tandem scFv-Fc fusion protein and cotinine-crosslinked magnetic beads significantly reduced the amount of protein contaminants compared with a parallel experiment done with protein A agarose beads. In subsequent immunoblot analysis, use of cotinine-HRP as the secondary probe instead of HRP-conjugated goat anti-rabbit IgG (Fc-specific) antibody successfully eliminated the band corresponding to the bispecific tandem scFv-Fc fusion protein.
Animals ; Antibodies, Bispecific/*immunology ; HEK293 Cells ; Haptens/*immunology ; Humans ; Immunoblotting/*methods ; Immunoprecipitation/methods ; Rabbits ; Single-Chain Antibodies/immunology

To enhance the specificity of anti-TNF-α single chain Fv antibody (TNF-scFv) to inflamed site, we constructed a bispecific antibody BsDb that targets TNF-α and ED-B-containing fibronectin (B-FN) by covalently linking TNF-scFv and the anti-ED-B scFv L19 at the gene level via a flexible peptide linker deriving from human serum albumin. BsDb was successfully secreted from Pichia pastoris as functional protein, identified by immunoblotting, and purified to homogeneity with affinity chromatography. BsDb retained the immunoreactivity of its original antibodies TNF-scFv and L19, and showed a marked gain in antigen-binding affinity and in TNF-α-neutralizing ability, when compared to TNF-scFv and L19 that were produced in Escherichia coli. In the adjuvant-induced arthritis (AIA) mice model, BsDb showed selective accumulation and retention in the inflamed paws but rapid clearance from blood, resulting in high arthritic paw to blood ratios. These data indicate that BsDb is endowed with high specificity to inflamed site and low toxicity to normal tissues and holds great potential for in vivo application for the targeted therapy of RA and other chronic inflammatory diseases.
Animals ; Antibodies, Bispecific ; biosynthesis ; immunology ; Antibodies, Neutralizing ; biosynthesis ; immunology ; Escherichia coli ; Fibronectins ; chemistry ; immunology ; Humans ; Mice ; Single-Chain Antibodies ; biosynthesis ; immunology ; Tumor Necrosis Factor-alpha ; immunology

Tumor surface antigen human epidermal growth factor receptor 2 (Her2) is a type I receptor tyrosine kinase, which belongs to human epidermal growth factor receptor family. Her2-overexpression is associated with tumorigenesis and metastasis. Due to significant clinical effects, Her2-targeted cancer therapy especially therapeutic antibody has become the hot spot in the field of cancer treatment. Anti-Her2 antibody drugs include monoclonal antibodies, antibody-drug conjugates, bispecific antibodies and emerging "two in one" antibody. Based on structure and function of Her2, this review focuses on recent advances in active mechanisms and clinical researches of these antibodies.
Antibodies, Bispecific ; therapeutic use ; Antibodies, Monoclonal ; therapeutic use ; Humans ; Immunoconjugates ; therapeutic use ; Neoplasms ; drug therapy ; Receptor, ErbB-2 ; immunology

After having successfully constructed and expressed the gene of the anti-CD3/anti-CD20 bispecific single-chain antibody (bscCD3 x CD20), here we analyzed its in vitro bioactivity of mediating the lysis of Ramous human B-lymphoma cells in the presence of T-enriched human peripheral blood lymphocytes (PBL). Obvious opoptosis characters were observed by Annexin V/PI(AV/PI) stained and scanning electron microscope. As evaluated by non-radioactive cytotoxity assay, the bscCD3 x CD20 showed potent bioactivity of mediating human B-lymphoma cells lysis in the presence of T-enriched human PBL. The potency of cytotoxicity depended on the ratios of effect cells to target cells (E:T) used. Further, the antibody showed a dose and time-dependent effect on mediating Ramous cells lysis. The specific lysis reached about 87.3% at an antibody concentration of 5microg/mL and E:T used at 10:1. Clear changes in apoptogenes expression profiles were detected by apoptosis gene array after Ramous cells were treated with the antibody and PBL. Among the upregulated apoptogenes, ATM and P53 showed an increase of 187 times and 15 times respectively, which suggested that ATM-p53 pathway may be the main apoptosis way of Ramous cells induced by T cells in the presence of the bscCD3 x CD20.
Antibodies, Bispecific ; immunology ; Antigens, CD20 ; immunology ; Apoptosis ; immunology ; CD3 Complex ; immunology ; Humans ; Lymphoma, B-Cell ; immunology ; pathology ; T-Lymphocytes, Cytotoxic ; immunology ; Tumor Cells, Cultured

Bispecific antibodies have been exploited as both cancer immunodiagnostics and cancer therapeutics, which have shown promises in clinical trials in cancer imaging and therapy. To improve the anti-tumor effect, an scDb (bispecific single-chain diabody) was constructed from the variable domain genes of two scFvs (single-chain variable fragment antibodies) directed against human EGFR (epidermal growth factor receptor) and VEGFR2 (vascular endothelial growth factor receptor 2) extracellular domains. The anti-EGFR/ anti-KDR scDb was constructed into pHEN2 plasmid and expressed in Escherichia coli HB2151 host. After purification by one-step affinity chromatography of IMAC, scDb protein was characterized by Western blotting. The yield of scDb protein was 570 microg per liter medium. scDb bound to EGFR as efficiently as the parental antibody scFv-E10, while a little bit weaker than the parental antibody scFv-AK404R when bound to KDR. In conclusion, the scDb protein could bind both EGFR and KDR specifically and could be applied for further anti-tumor research.
Antibodies, Bispecific ; biosynthesis ; genetics ; Escherichia coli ; metabolism ; Humans ; Plasmids ; Protein Binding ; Receptor, Epidermal Growth Factor ; immunology ; Single-Chain Antibodies ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor Receptor-2 ; immunology

OBJECTIVETo study and compare the biologic activity of two anti-PSA/anti-CD3 bispecific single-chain antibodies.

METHODSFlow cytometry (FCM) was used to detect the binding activity of two antibodies to CD3-positive cell line Jurkat and prostate carcinoma cell line LNCaP. The effect of the two antibodies in mediating tumor cell lysis in vitro was determined by using the 51Cr-release test. For in vivo evaluation of the two antibodies activity, a nude mouse model was used. The mice were inoculated with LNCaP prostate cancer cells.

RESULTSFCM showed that both the antibodies could bind Jurkat and LNCaP cells with high specificity. The percentages of the cells bond by the bispecific single-chain antibodies were 56.3% and 55.4%, and those by the multivalent antibodies were 74.0% and 83.0% respectively. Both the antibodies mediated a specific lysis of LNCaP cells in vitro, with activated CTLs as effector cells, and significantly reduced tumor growth of nude mice in vivo as compared with the untreated controls and the group treated with CTLs only (P <0.05). The experiment also showed that the multivalent antibody had a better activity than the bispecific antibody in binding antigens, mediating lysis of LNCaP cells and reducing tumor growth (P < 0.05).

CONCLUSIONBoth the anti-PSA/anti-CD3 bispecific single-chain antibody and multivalent antibody have good biologic activity, and the formation of the tetramerization of single-chain antibody can improve its biologic activity.

Animals ; Antibodies, Anti-Idiotypic ; immunology ; Antibodies, Bispecific ; immunology ; pharmacology ; CD3 Complex ; immunology ; Cytotoxicity, Immunologic ; immunology ; Flow Cytometry ; Humans ; Jurkat Cells ; Male ; Mice ; Mice, Nude ; Prostate-Specific Antigen ; immunology ; Prostatic Neoplasms ; immunology ; pathology

OBJECTIVETo analyze the drift of T cell receptor (TCR) Vα and Vβ gene family CDR3 spectratype in response to ovarian carcinoma cells mediated by an anti-human ovarian carcinoma/CD3 bispecific single-chain antibody (BHL-1), and explore the mechanism of the bispecific single-chain antibody-mediated T cell immune response.

METHODSImmunoscopic spectratyping technique was used to analyze the TCR repertoire diversity (CDR3 spectratype distribution) of the T cells from 6 healthy donors before and after stimulation of the cells with human ovarian carcinoma in the presence of BHL-1. The predominant usage of TCR α and Vβ chain CDR3 was analyzed after the stimulation, and sequence analysis was performed for the CDR3 region of the monoclonal T cells.

RESULTSThe spectratypes of Vα and Vβ gene family TCR CDR3 region showed a Gaussian distribution before stimulation of the T cells from the 6 donors. After stimulation of the T cells, CDR3 spectratype drift occurred in the T cells, and some TCR Vα and Vβ families showed an anomalous and oligoclonal expansion. Different CDR3 sequences of the Vα and Vβ gene family TCR were found in the monoclonal T cells stimulated with BHL-1.

CONCLUSIONCDR3 spectratype drift occurs in TCR α and Vβ chains of T cells after stimulation with human ovarian carcinoma cells and BHL-1, indicating that the predominant usage of TCR Vα and Vβ families is associated with the specific T cell immune response mediated by BHL-1.

Antibodies, Bispecific ; immunology ; Cell Line ; Cell Line, Tumor ; Complementarity Determining Regions ; immunology ; Female ; Humans ; Monocytes ; immunology ; Ovarian Neoplasms ; immunology ; Receptors, Antigen, T-Cell, alpha-beta ; immunology ; Single-Chain Antibodies ; immunology

The synthetic gene with 1640bp encoding for the anti-CD3/anti-CD20 bispecific single-chain antibody was designed and obtained by SOE (splicing by overlap extension) PCR. The cDNA was cloned into Flp-In expression vector pcDNA5/FRT and transfeced into Flp-In CHO cells to generate a stable expression cell line with a capacity for expressing anti-CD3/anti-CD20 bispecific single-chain antibody at 300 microg/L. The protein, which had a molecular weight of about 70 kD,was purified by Ni-NTA affinity chromatography and identified by SDS-PAGE and Western-blot analysis. Immunofluorescence assay and cellular rosetting showed that it can react specifically on Jurkat (CD3+) and Ramous (CD20+) cells. The lysis of human PBL against CD20-positive lymphoma Ramous cells in the presence of the anti-CD3/anti-CD20 bispecific single-chain antibody can observed by microscope. All these results would lighten the further study of its biological functions in vitro and in vivo.
Animals ; Antibodies, Bispecific ; biosynthesis ; genetics ; immunology ; Antibodies, Monoclonal ; immunology ; Antigens, CD20 ; immunology ; CD3 Complex ; immunology ; CHO Cells ; Cricetinae ; Cricetulus ; Humans ; Immunoglobulin Variable Region ; biosynthesis ; genetics ; immunology ; Lymphoma, B-Cell ; metabolism ; Recombinant Proteins ; Transfection ; Tumor Cells, Cultured

Novel biologics that redirect cytotoxic T lymphocytes (CTLs) to kill tumor cells bearing a tumor associated antigen hold great promise in the clinic. However, the ability to safely and potently target CD3 on CTL toward tumor associated antigens (TAA) expressed on tumor cells remains a challenge of both technology and biology. Herein we describe the use of a Half DVD-Ig format that can redirect CTL to kill tumor cells. Notably, Half DVD-Ig molecules that are monovalent for each specificity demonstrated reduced non-specific CTL activation and conditional CTL activation upon binding to TAA compared to intact tetravalent DVD-Ig molecules that are bivalent for each specificity, while maintaining good drug like properties and appropriate PK properties.
Animals ; Antibodies, Bispecific ; immunology ; Antibodies, Monoclonal ; immunology ; pharmacokinetics ; CD3 Complex ; metabolism ; Cell Line, Tumor ; Cytotoxicity, Immunologic ; ErbB Receptors ; metabolism ; Female ; Humans ; Lymphocyte Activation ; immunology ; Mice, SCID ; Neoplasms ; immunology ; pathology ; Rats, Sprague-Dawley ; T-Lymphocytes, Cytotoxic ; immunology

OBJECTIVETo study the specific targeting cytotoxicity to drug-resistant leukemia cells mediated by anti-Pgp/anti-CD3 diabody.

METHODSThe diabody was purified by affinity chromatography and identified by SDS-PAGE and FACS. The effect of the anti-Pgp/anti-CD3 diabody mediated lysis of Pgp-expressing tumor cells was assayed by human leukemia nude mice xenograft model in vivo.

RESULTSThe diabody was produced in E.coli in a soluble functional form and could bind both Jurkat cells (CD3(+)) and K562/A02 cells (Pgp(+)). The binding rates were 86.25% and 86.26%, respectively. It could inhibit tumor growth by 98.57% and prolonged the survival of mice bearing xenografted K562/A02 cells.

CONCLUSIONThe diabody was proved to be a potent agent for mediating T lymphocyte cytotoxicity to lyse Pgp expressing tumor cells in vitro and in vivo.

ATP-Binding Cassette, Sub-Family B, Member 1 ; immunology ; Animals ; Antibodies, Bispecific ; immunology ; pharmacology ; CD3 Complex ; immunology ; Cytotoxicity, Immunologic ; drug effects ; Drug Resistance, Neoplasm ; immunology ; Humans ; Jurkat Cells ; Mice ; Mice, Nude ; T-Lymphocytes ; drug effects ; immunology ; Xenograft Model Antitumor Assays