A monoclonal antibody against human UL16-binding protein 3

The UL16-binding proteins (ULBPs) are a novel family of human MHC class I-related, cell surface proteins that function as ligands for NKG2D. In this study, the gene encoding human ULBP3 was cloned into prokaryotic expression vector pQE30, resulting in a recombinant plasmid pQE30-ULBP3. The pQE30-ULBP3 was transformed into Escherichia coli M15 and induced the expression of recombinant protein ULBP3 (rec-ULBP3). The purified rec-ULBP3 as an antigen was used to immunize BALB/c mice. Through cell fusion, sub-cloning, and screening approach, three hybridoma cell clones expressing monoclonal antibodies (MAb) were acquired. The results from Western blot analysis, flow cytometry, and enzyme-linked immunosorbent assay showed that the hybridoma clones B2-F1-F1 and B4-C5-D11, and not G2-A4-A12, reacted with rec-ULBP3 and nature ULBP3 expressed on the cell surface of the tumor cells. In conclusion, the new MAb described here provides a valuable tool for further investigating ULBP3 function and clinical application.