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LIGHT Is critical for IL-12 production by dendritic cells, optimal CD4+ Th1 cell response, and resistance to Leishmania major.

Xu G, Liu D, Okwor I, Wang Y, Korner H, Kung SK, Fu YX, Uzonna JE.

Department of Immunology, Faculty of Medicine University of Manitoba, Winnipeg, Canada.

Although studies indicate LIGHT (lymphotoxin (LT)-like, exhibits inducible expression and competes with HSV glycoprotein D for herpes virus entry mediator (HVEM), a receptor expressed by T lymphocytes) enhances inflammation and T cell-mediated immunity, the mechanisms involved in this process remain obscure. In this study, we assessed the role of LIGHT in IL-12 production and development of CD4(+) Th cells type one (Th1) in vivo. Bone marrow-derived dendritic cells from LIGHT(-/-) mice were severely impaired in IL-12p40 production following IFN-gamma and LPS stimulation in vitro. Furthermore, blockade of LIGHT in vitro and in vivo with HVEM-Ig and LT beta receptor (LTbetaR)-Ig leads to impaired IL-12 production and defective polyclonal and Ag-specific IFN-gamma production in vivo. In an infection model, injection of HVEM-Ig or LTbetaR-Ig into the usually resistant C57BL/6 mice results in defective IL-12 and IFN-gamma production and severe susceptibility to Leishmania major that was reversed by rIL-12 treatment. This striking susceptibility to L. major in mice injected with HVEM-Ig or LTbetaR-Ig was also reproduced in LIGHT(-/-) --> RAG1(-/-) chimeric mice. In contrast, L. major-infected LTbeta(-/-) mice do not develop acute disease, suggesting that the effect of LTbetaR-Ig is not due to blockade of membrane LT (LTalpha1beta2) signaling. Collectively, our data show that LIGHT plays a critical role for optimal IL-12 production by DC and the development of IFN-gamma-producing CD4(+) Th1 cells and its blockade results in severe susceptibility to Leishmania major.

Publication Types:
PMID: 17982081 [PubMed - indexed for MEDLINE]