ILDR2-Fc Is a Novel Regulator of Immune Homeostasis and Inducer of Antigen-Specific Immune Tolerance.

ILDR2 is a member of the Ig superfamily, which is implicated in tricellular tight junctions, and has a putative role in pancreatic islet health and survival. We recently found a novel role for ILDR2 in delivering inhibitory signals to T cells. In this article, we show that short-term treatment with ILDR2-Fc results in long-term durable beneficial effects in the relapsing-remitting experimental autoimmune encephalomyelitis and NOD type 1 diabetes models. ILDR2-Fc also promotes transplant engraftment in a minor mismatch bone marrow transplantation model. ILDR2-Fc displays a unique mode of action, combining immunomodulation, regulation of immune homeostasis, and re-establishment of Ag-specific immune tolerance via regulatory T cell induction. These findings support the potential of ILDR-Fc to provide a promising therapeutic approach for the treatment of autoimmune diseases.