Production and characterization of a bacterial single-chain Fv fragment specific to human truncated midkine

The production (and characterization) of a monoclonal antibody against huma n truncated midkine (tMK), and the detection of tMK in G401 cells, a Wilms' tumor cell line, as well as in Wilms' tumor patient specimens, have been r eported (Paul et al., Cancer Lett. 163 (2001) 245-251). Here we report the molecular cloning and expression of this monoclonal antibody as a single-ch ain Fv fragment (scFv) in Escherichia coli. The scFv protein, purified by i mmobilized metal affinity chromatography, showed a specific affinity to rec ombinant tMK and native tMK in G401 cells as detected by enzyme-linked immu nosorbent assay and immunofluorescence microscopy, respectively. The bindin g of this protein to recombinant tMK was competitive with the parental mono clonal antibody. These results suggest that this scFv can also be used for Wilms' tumor detection. (C) 2001 Elsevier Science Ireland Ltd. All rights r eserved.