Dimeric scFv Antibody construct of ior-CEA1 aspotential agent for therapeutic application

摘要

In the present study, it is reported the generation of a divalent single-chain Fv (scFv)2 ofrnthe murine Mab ior-CEA1 that recognizes the CEA-expressing colon carcinoma tumours. This scFvrnvariant was expressed in the periplasm of the Escherichia Coli and purified as soluble protein. The inrnvitro binding properties of the divalent construct were analyzed by immunoreactivity studies andrnScatchard plot. The binding affinity constant (Ka) for the radioiodinated (scFv)2 was 3.5 x 107 M-1,rnsimilar to other authors. Radiolabelled protein was injected into mice bearing CEA-positive LS174Trntumours, and biodistribution was carried out at various time points after injection. The maximalrntumour uptake was at 4 h (7.07 ± 2,2 %ID/g). The tumor:blood ratio at 24 h for the diabody was 5.7:1,rnwhich increased to 8:1 at 48 h. The normal tissues displayed low non-specific binding and no crossreaction.rnThese results demonstrate that the ior-CEA1 diabody construct may have potentialrnapplication for diagnosis and therapeutic use.