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- Erlandsson, Ann, et al.
(författare)
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In vivo clearing of idiotypic antibodies with antiidiotypic antibodies and their derivatives
- 2006
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Ingår i: Molecular Immunology 2006;42:599-604.
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Tidskriftsartikel (refereegranskat)abstract
- At immunolocalization of experimental tumors, idiotypic monoclonal antibodies, such as TS1 against cytokeratin 8, can be used to carry and deposit in vivo terapeutics in the tumor. These carriers also remain in the circulation and may cause negative side-effects in other tissues.In this report, several derivatives of the antiidiotypic antibody anti-TS1 were produced and tested for their clearing capacity of the idiotypic carrier antibody TS1. Intact monoclonal anri-TS1, scFv of a anti-TS1 and anti-TS1 Fab and Fab'2 fragments were produced by recombinant technology or by cleavage with Ficin. The scFv was tailored by use of the variable domain genes of the light and heavy chain from the hybridoma clone in combination with a (Gly4Ser)3-linker, followed by expression in E. coli. When tested for clearing capacity, the intact divalent antiidiotypic IgG was found to be the most efficient. The divalent Fab'2 and the monovalent Fab fragment also demonstrated significant clearing, but lower than the intact antiidiotypic IgG. The anti-TS1 scFv antibody when injected separately was not found to clear the idiotype, but could do so when preincubated with the idiotype. Rapid excretion and in vivo instability of this lowmolecular weight antibody fragment may be the major reasons. Similar results were obtained when the system was reversed and the 131I-labeled antiidiotype IgG was cleared with the idiotype Fab'2 fragment. It is concluded that both intact antiidiotypic IgG, Fab'2 and Fab fragments are able to clear the idiotypic antibodies. The experimental data support the conclusion that the Fc parts from both the idiotype and the antiidiotype may contribute to this elimination
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- Holm, Patrik
(författare)
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Single-chain antibody construction and functional mapping of the monoclonal antibody TS1 : Its interaction with the antigen and the anti-idiotype
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of this study are to synthesize and produce a single-chain antibody (scFv) of the anti-cytokeratin 8 monoclonal IgG antibody TS1 and to functionally map amino acid residues important for the interaction with its antigen and the anti-idiotypic antibody TS1. The TS1 antibody has been shown to be effective in binding cytokeratin 8 (CK8) expressed in tumors in vivo and is proposed to be useful in immunotargeting and/or immunotherapy. The anti-idiotypic antibody TS1 can be used to regulate the tumor:non-tumor ratio. Mutagenesis of certain amino acid residues can be used to alter the affinity to improve the tumor:non-tumor ratio further. In the present study, the TS1 IgG was chemically modified to specify groups of residues important for interaction with both CK8 and TS1. If important residues were found in the CDRs, they were mutated in the TS1 scFv construct and the effect was studied using ELISA. The main conclusions drawn from this study are that the important amino acid residues in TS1 for the interaction with both CK8 and TS1 are mainly tyrosines, charged residues and a tryptophan. A central interacting interface was identified with the somewhat unusual participation of residues in the CDR 2 of the light chain. Mutations which resulted in increased affinity to both CK8 and TS1 were also identified.
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- Jafari, Rozbeh, 1977-
(författare)
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Construction, expression and evaluation of anti-keratin 8 single-chain antibody fragments
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibodies are glycoproteins specifically binding to a variety of antigens and today extensively used in prevention, diagnosis and treatment of diseases. Carcinomas originate from epithelial tissues and are the most common forms of human malignancies. In the necrotic areas of carcinomas significant amounts of keratins (K) are found extracellularly. They remain there due to their low solubility and can be used as targets in immuno-targeting and -therapy. Single-chain fragment variable (scFv) may display several advantages over intact IgGs in various applications but their use in immunotherapy of tumors could be limited. Their small size and monovalency may result in low accumulation of the scFv in the tumors. The targeting efficiency of antibodies needs to be evaluated in vitro prior to in vivo studies in order to exclude poor candidates. In vitro models should preferably resemble the in vivo situation as much as possible. In the present study a scFv variant (TS1-218) of the anti-keratin 8 (K 8) monoclonal antibody TS1 (mAb TS1) was constructed and characterized using site-directed mutagenesis. In addition, the valency of the TS1-218 and one of its mutants, HE1-Q, were increased by construction of a covalently linked divalent single-chain fragment variable (sc(Fv)2). To improve the yield of the antibody fragments, the expression host was changed from E. coli to P. pastoris and culture conditions were optimized using Design of Experiments (DoE). Furthermore, a HeLa HEp-2 multicellular tumor spheroid (MCTS) in vitro model was established. The functionality of the radiolabeled TS1-218 alone and in immunocomplex with its anti-idiotype scFv, αTS1 scFv, were evaluated in the MCTS model and compared to a tumor xenograft nude mouse model. The targeting efficiency of the scFv and sc(Fv)2s were also investigated using MCTS. TS1-218 in immunocomplex with αTS1 scFv displayed a significantly higher uptake than the TS1-218 alone in both MCTS and tumor xenografts. The sc(Fv)2s, DiTS1-218 and DiHE1-Q demonstrated a higher functional affinity to K 8 in ELISA and MCTS and were retained to a larger extent in the MCTS than their scFv counterparts, with a 3.9 and 9.4-fold longer half-life, respectively. Furthermore, the yield of the antibody fragments were improved after expression in P. pastoris with an 86-fold improvement for the TS1-218 following optimization using DoE.
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- Jafari, Rozbeh, 1977-, et al.
(författare)
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Construction of divalent anti-keratin 8 single-chain antibodies (sc(FV)2), expression in Pichia Pastoris and their reactivity with multicellular tumor spheroids
- 2011
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Ingår i: JIM - Journal of Immunological Methods. - : Elsevier BV. - 0022-1759 .- 1872-7905. ; 364:1-2, s. 65-76
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Tidskriftsartikel (refereegranskat)abstract
- Single-chain variable fragments (scFvs) are small monovalent recombinant antibody fragments that retain the specificity of their parent immunoglobulins. ScFvs are excellent building blocks for new and improved immunodiagnostic and therapeutic proteins. However, the monovalency and the rapid renal elimination of scFvs result in poor tumor accumulation and retention. Engineering divalent antibody fragments is an excellent way to address these shortcomings. In this study, covalent divalent single-chain variable fragments (sc(Fv)2s), were constructed from the monovalent anti-keratin 8 scFvs, TS1-218 and its mutant, HE1-Q. The scFvs and sc(Fv)2s were expressed in the methylotrophic yeast Pichia pastoris, utilizing the alpha-factor secretion signal (α-factor) for extracellular secretion. The immunoreactivity and specificity of the antibody fragments were analyzed with enzyme-linked immunosorbent assay (ELISA) and the uptake and retention of the 125I labeled antibody fragments were evaluated using HeLa HEp-2 multicellular tumor spheroids (MCTSs). Analysis of the antibody fragments demonstrated that parts of the α-factor remained at the N-terminal of the antibody fragments. Despite incomplete processing of the α-factor, the antibody fragments were functional where the sc(Fv)2s gave a three-fold stronger signal in ELISA compared to their scFv counterparts and the mutant antibodies demonstrated a stronger signal than their initial wild types. In addition, the sc(Fv)2s DiTS1-218 and DiHE1-Q displayed an approximately two-fold higher uptake and were retained to a larger extent in the MCTS, demonstrating a 3.9 and 9.4-fold increase in half-life respectively compared to their corresponding scFvs. In conclusion, expression in P. pastoris improved the yield 20-fold and facilitated the purification of the antibody fragments. Furthermore, the sc(Fv)2s presented a higher functional affinity to K 8 both in ELISA and MCTS compared to the scFvs with DiHE1-Q being the best candidate for further studies.
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