SINGLE-CHAIN ANTIBODY VARIABLE REGION-TARGETED INTERLEUKIN-2 STIMULATES T-CELL KILLING OF HUMAN COLORECTAL-CARCINOMA CELLS

Recombinant DNA techniques were used to clone, construct and express t he bifunctional molecule FV/IL-2. The FV/IL-2 is a single-chain 37 kDa fusion protein expressed in Escherichia coli under control of the str ong T7 bacteriophage promoter in the expression vector pT7-7-FV-IL-2. The fused gene fragment FV-IL-2 contains a single-chain anti-TAG72 FV gene fragment and the human recombinant cDNA fragment of the IL-2 mole cule. The renatured soluble form of FV/IL-2 was purified from E. coli inclusion bodies using hydroxylapatite chromatography. The yield of th is fusion protein was estimated at 2.0 mg/L. Our data showed that the FV/IL-2 molecule retained the TAG72 antigen-binding specificity and th e IL-2 activity as measured in the standard T cell proliferation as we ll as cytotoxicity assays. Therefore, it may prove to be useful in tar geting the biological effect of IL-2 to tumour cells and stimulating i ts immune destruction.