Type I interferon induced by lymphotoxin-beta receptor signaling on dendritic cell is crucial for CD8 T cell infiltration into effector site by modulating the expression of tissue specific adhesion molecule VLA4 (P5045)

Abstract In non-infectious settings with minimal inflammatory stimulus, CD4 T cell help is needed for dendritic cells (DC) to cross-prime antigen in order to elicit a CD8 T cell response. Activated CD4 T cells express CD40-ligand (CD40L) and lymphotoxin-α1β2 (LTαβ), which interacts with their respective TNF receptors, CD40 and lymphotoxin-β receptor (LTβR) on DC, thereby significantly increases the DC immunogenic potential. Our early work showed that LTβR signaling induces Type I IFN expression in DC which facilitates CD8 T cell expansion against soluble protein antigen. In this study, we identified that LTβR signals through TNF receptor-associated factor (TRAF)-3 for interferon regulatory factor (IRF)-3 phosphorylation and Type I IFN production. Furthermore, using an inducible diabetes model through the transfer of activated DC, we found that LTβR signaling on DC is absolutely required for the proper priming of CD8 T cells and diabetes induction. We further showed that LTβR-induced Type I IFN affect the expression of the adhesion molecule VLA-4 on antigen specific CD8 T cells and it affects their ability to infiltrate into the pancreas. LTβR deficient DC fail to induce diabetes, and the provision of exogenous IFN-α was sufficient to rescue the diabetes status. Together, these results describe a novel role for LTβR in the induction of Type I IFN by DC, and demonstrate its relevance in an autoimmune setting.