Antigen-presenting function and B7 expression of murine sinusoidal endothelial cells and Kupffer cells

Background & Aims: Inflammatory liver disease as well as rejection of liver allografts are thought to be mediated by resident antigen-presenting cells in the liver. At the same time, in vivo antigen presentation in the liver appears to be a more tolerogenic than systemic antigen challenge. The aim of this study was to show and characterize the antigen-presenting capability of sinusoidal endothelial cells and Kupffer cells. Methods: Purified murine sinusoidal endothelial cells and Kupffer cells were studied for their ability to serve as accessory cells and antigen-presenting cells by proliferation assays. They were also studied for their expression of interleukin 1 and the B7 costimulatory molecules by Northern blotting, polymerase chain reaction, and flow cytometry. Results: Both cell types expressed interleukin 1 messenger RNA and could serve equally well as accessory and antigen-presenting cells. B7-2 messenger RNA and surface expression on sinusoidal endothelial cells and on Kupffer cells was shown. Antibodies to the B7 molecules inhibited antigen presentation. Addition of interleukin 10 as a regulatory cytokine secreted by Kupffer cells was suppressive. Conclusions: Sinusoidal endothelial cells carry functional B7-2 molecules and can serve as effective antigen-presenting cells. However, antigen presentation by sinusoidal endothelial cells may be locally down-regulated by interleukin 10.