Study On The Distribution, Function And Its Mechanisms Of 9.1C3 Molecule, A Novel NK Cell Inhibitory Receptor

Monoclonal antibody 9.1C3 was raised by immunizing mice with human natural killer cells. This mAb can inhibit the natural cytotoxicity of NK cells either from PBMC or generated from mixed lymphocyte culture (MLC). However, detail information about the mAb recognized molecule 9.1C3 is not very clear. Study on the distribution, function and its mechanism of this molecule is of interests.First of all, the distribotion profile of 9.1C3 molecule was investigated and it was found that this molecule was expressed on PBMC, T cell lines, some NK cell lines, and a few myeloid cell lines, but not on B cell lines and majority of myeloid cell lines.As for the function study, the redirected cytotoxicity assay (RCA) was employed, in which murine FcR~+ mastsarcoma P815 cell line was used as target cells. We used PBMC as effectors, and found that CD16 mAb can induce the cytotoxicity, which was inhibited markedly at the presence of 9.1C3 mAb suggesting that 9.1C3 molecule may be a NK cell inhibitory receptor. Then, the MLC cells were used as effectors in the RCA. We found that MLC cells can lysis the P815 directly to some extent. The cytotoxicity was increased significantly when MLC cells were pre-incubated with CD2 or CD16 mAb, and the natural cytotoxicity or antibody-induced cytotoxicity were inhibited dramatically when 9.1C3 mAb was added into RCA at the same time. The inhibitory effect of 9.1C3 on CD16-induced cytotoxicity was mAb dose-dependent. Besides the cytotoxicity, the secretion of TNF-α during the killing phase was also inhibited by 9.1C3 mAb. However, CD3-induced cytotoxicity was not changed obviously at the presence of 9.1C3 mAb. Since the killer cells generated from MLC include NK cells and T...