Sepsis is a complex clinical condition caused by a dysregulated immune response to an infection. However, the mechanism by which our immune system controls this amplified inflammation is largely unknown. In this study, we investigated whether Tim-3 pathway could serve as a negative mediator in lipopolysaccharide (LPS)-induced endotoxic shock. Our results showed that Tim-3 was expressed on CD4(+) T cells, CD8(+) T cells, and NK cells, and was significantly increased in the peritoneal cavity of septic mice. Tim-3 acted as a marker of immune exhaustion and Tim-3-positive T cells and NI(cells had a lower interferon (IFN)-gamma production. Furthermore, blockade of Tim-3 pathway significantly accelerated mortality in septic mice, while activation of this pathway prolonged survival time. In vitro administration of Tim-3 blocking antibody restored the release of IFN-gamma from splenocytes and decreased splenocyte apoptosis, and increased levels of IFN-gamma and tumor necrosis factor (TNF)-alpha were also detected in septic mice at 24 h post in vivo administration of the antibody. In contrast, activation of Tim-3 pathway prevented cell proliferation. Thus, Tim-3 signaling pathway acts as a novel negative mediator in LPS-induced endotoxic shock and could be a potential therapeutic target for the treatment of sepsis. (C) 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.