Galectin-9（Tim-3L） significantly attenuates aUogeneic immune response in mice
Objective To explore the subcellular localization of Galectin-9 and its effect on allogeneic immune response. Methods The plasmid pEGFP-N1 was inserted with Galectin-9 fragment which was amplified from pBKCMV-Galectin-9 by PCR. The recombinant plasmid was then transfected into CHO cells using JetPEl in vitro. The cells were cultured in G418 selecting medium to obtain the stably-transfected cells. The transcription and expression of Galectin-9 gene were verified by immunohistochemical staining and RT-PCR. The solid-phase transgenic CHO cells or freshly-cultured supernatant was added into the mixed lymphocyte response system to detect the inhibitory effect of Galectin-9. Galectin-9 protein was administered intraperitoneally for 7 d consecutively. Results The expression of Galectin-9 was localized in the cytosol of CHO. The allogeneic mix lymphocyte proliferation was dose-dependently inhibited by the freshly-cultured su- pernatant from stably-transfected CHO cells. Furthermore, the supernatant from stably-transfected CHO cells dose-dependently inhibited the level of IL-2. The inhibitory effect could be reversed by Tim-3-Fc blocking. Administration of Galectin-9 significantly prolonged the survival of allogeneic cardiac transplants [ （22.7 ± 1.2） d vs （7.2 ± 0.4） d） ]. Conclusion Galectin-9 may be secreted in physical situation to exert its im- munomodulatory function on allogeneic immune response. Furthermore, Galectin-9 may be a novel therapeutic drug in transplant medicine. 
 
Key words: 
Tim-3;  Galectin-9;  Immunosuppression;  Mouse