Cooperative IFN-γ production of mouse liver B cells and natural killer cells stimulated with lipopolysaccharide

Background/Aims: Although mouse liver contains a large population of B cells, little is known about how hepatic B cells respond to bacteria] lipopolysaccharide (LPS). Methods: The cytokine and IgM productions of hepatic B cells were compared with those of splenic B cells. The effect of LPS-treated hepatic B cells on IFN-gamma production from co-cultured NK1.1(+) cells was also examined by irradiation and transwell experiments. Results: Hepatic B cells stimulated with LPS produced substantial amounts of IFN-gamma and IL-12 but a small amount of IgM, while splenic B cells did not produce any of these cytokines but produced a large amount of IgM. The hepatic B cells expressed surface markers similar to those on spleen B cells but expressed more C-X-C chemokine receptor 3 than spleen B cells. Notably, depletion of B220(+) cells from liver MNCs (but not from spleen NINCs) greatly decreased LPS-induced IFN-gamma production. Furthermore, LPS-treated hepatic B cells stimulated liver NK1.1(+) cells to produce a remarkable amount of IFN-7, not only through their soluble factors but also through direct cell-cell contact. Conclusions: Liver B cells may play an important role in the defense against gram-negative bacterial infections by inducing IFN-gamma production from liver NK cells. (c) 2006 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.