| Antibodies are one of the most useful molecules with affinity of binding and specificity for in vitro and in vivo diagnosis, or for immunotherapy of human diseases. In recent years, phage-displayed antibody library has been widely adopted to select tailor-made antibodies in a fast, high-throughput mode, as an alternative of traditional hybridoma technology. Although phage display has been introduced for about 20 years, the applications and development of this technology still have a rich space to be explored.;Attempts are made in the present study to extend three applications of the phage displayed antibody library in antibody discovery and engineering. Firstly, a CDR3-randomized phage-displayed scFv library was constructed from genomic DNA of mouse. Following biopanning, anti-peptide of mas oncoprotein scFvs were isolated and identified. These results illustrate the potential use of the genomic phage-displayed library for anti-peptide antibodies selection. Secondly, we described the isolation of anti-idiotypic scFvs against a chimeric anti-CD22 mAb from an immunized phage-displayed scFv library. The isolated anti-Id scFvs were able to capture the immune response of chimeric anti-CD22 mAb with high specificity. This reagent will enhance our understanding of the therapeutic mechanism of anti-CD22 mAb in non-Hodgkin's lymphoma treatment, and may be applied to probe the pharmacokinetics, tissue distribution, and modulation of anti-CD22 mAb in vivo.;Our approach enables us to isolate selective and sensitive anti-idiotypic antibodies and could be exploited for other antibodies with clinical and biological applications. Thirdly, we profile a strategy to select and identify markers on tumor cell surface using phage-displayed antibodies from mice bearing xenograft tumor. Our data imply that passive antibodies in cancer patients may be obtained from the immune repertoire of cancer patients. Besides, we found a cell surface antigen was up-regulated more than 3-fold in mas-expressing cells. We further use the targeting antibody to construct a tumor endoprotease-activated immunotoxin.;In conclusion, we have attempted various approaches to identify specific anti-peptide scFvs, anti-idiotypic scFvs and passive anti-tumor scFvs. These results extend the applications of phage display technology in antibody discovery and engineering. |
