Systemic Antigen Cross-Presented by Liver Sinusoidal Endothelial Cells Induces Liver-Specific CD8 T-Cell Retention and Tolerization

Peripheral CD8 T-cell tolerance can be generated outside lymphatic tissue in the liver, but the course of events leading to tolerogenic interaction of hepatic cell populations with circulating T-cells remain largely undefined. Here we demonstrate that preferential uptake of systemically circulating antigen by murine liver sinusoidal endothelial cells (ILSECs), and not by other antigen-presenting cells in the liver or spleen, leads to cross-presentation on major histocompatibility complex (MHC) I molecules, which causes rapid antigen-specific naive CD8 T-cell retention in the liver but not in other organs. Using bone-marrow chimeras and a novel transgenic mouse model (Tie2-H-2K(b) mice) with endothelial cell-specific MHC I expression, we provide evidence that cross-presentation by organ-resident and radiation-resistant LSECs in vivo was both essential and sufficient to cause antigen-specific retention of naive CD8 T-cells under noninflammatory conditions. This was followed by sustained CD8 T-cell proliferation and expansion in vivo, but ultimately led to the development of T-cell tolerance. Conclusion: Our results show that cross-presentation of circulating antigens by LSECs caused antigen-specific retention of naive CD8 T-cells and identify antigen-specific T-cell adhesion as the first step in the induction of T-cell tolerance. (HEPATOLOGY 2009;49:1664-1672.)