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Medical Applications of Single-Chain Antibodies

 

作者: HustonJames S.,   McCartneyJohn,   ShengMei,   MottolaCristina,   JinDonald,   WarrenFrederick,   KeckPeter,   OppermannHermann,  

 

期刊: International Reviews of Immunology  (Taylor Available online 1993)
卷期: Volume 10, issue 2-3  

页码: 195-217

 

ISSN:0883-0185

 

年代: 1993

 

DOI:10.3109/08830189309061696

 

出版商: Taylor&Francis

 

关键词: single-chain Fv (sFv, scFv);single-chain antibody;sFv fusion proteins;immunotargeting

 

数据来源: Taylor

 

摘要:

A single-chain antibody or single-chain Fv (sFv) incorporates the complete antibody binding site in a single polypeptide chain of minimal size, with an approximate molecular weight of 26,000. In antibodies, the antigen combining site is part of the Fv region, which is composed of the VHand VLvariable domains on separate heavy and light chains. Efforts over nearly two decades have indicated that Fv fragments can only rarely be prepared from IgG and IgA antibodies by proteolytic dissection. Beginning in 1988, single-chain analogues of Fv fragments and their fusion proteins have been reliably generated by antibody engineering methods. The first step involves obtaining the genes encoding VHand VLdomains with desired binding properties; these V genes may be isolated from a specific hybridoma cell line, selected from a combinatorial V-gene library, or made by V gene synthesis. The single-chain Fv is formed by connecting the component V genes with an oligonucleotide that encodes an appropriately designed linker peptide, such as (Gly4-Ser)3. The linker bridges the C-terminus of the first V region and N-terminus of the second, ordered as either VH-linker-VLor VL-linker-VH. In principle, the sFv binding site can faithfully replicate both the affinity and specificity of its parent antibody combining site, as demonstrated in our model studies with the 26-10 anti-digoxin sFv. Furthermore, the sFv remains stable at low concentrations that promote VHand VLdissociation from the Fv heterodimer, resulting in loss of Fv binding. Intravenously administered sFv proteins exhibit accelerated biodistribution and exceptionally fast clearance compared to IgG or Fab. These pharmacokinetic properties allow rapid imaging by sFv, which therefore may be labeled with a shortlived isotope such as Tc-99m. Expression of a single gene product from fused sFv and effector genes facilitates immunotargeting of the effector protein, as shown for single-chain Fv toxin fusion proteins.

 

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