Liver sinusoidal endothelial cells (LSECs) isolated ex vivo by a novel MACS-based technology induce proliferation in naïve CD4+ T-cells and Th2 effector cells

The liver has been demonstrated to contribute to the induction of systemic tolerance by trapping, deletion or modulation of T-cells. This property seems to be at least partially mediated by liver sinusoidal endothelial cells (LSECs) since in vivo priming of CD8+ T-cells on LSECs leads to development of anergic T-cell subsets. Studying the function of endothelial cells (ECs) ex vivo usually meets experimental obstacles: isolation protocols are time consuming and require considerable technical equipment. Here we make use of the novel antibody ME-9F1 (murine endothelial cell antibody 9-F1) strongly reacting with mouse endothelium and report a simple antibody mediated, MACS-based ex vivo isolation technique which allows the preparation of LSECs in a short time and with a high purity (90–95%). Compared to the standard isolation protocol by centrifugal elutriation the MACS-based technology leads to comparable numbers and purity of cells. The isolated LSECs express a normal morphology in culture and are capable of antigen presentation in MHC II context. They induce antigen-specific proliferation in naive CD4+ T-cells as well as Th1/Th2 effector cells as shown by co-culture experiments with CFSE-labeled T-cell receptor transgenic T-cells. Compared to splenic antigen-presenting cells, they rather promote in vitro and in vivo survival and expansion of IL-4-expressing Th2 cells than Th1 cells. Taken together, our data support the point of view that LSECs are not only involved in tolerance induction in CD8+ but also CD4+ T-cell populations. Therefore, we speculate that the liver might especially play a role in tolerance induction to exogenous (food) antigens presented in MHC II context.