The immunomodulatory molecule and co-inhibitory receptor T cell immunoreceptor with Ig and ITIM domains (TIGIT) could be used to treat autoimmune diseases, according to results in a mouse model of lupus. Treatment of NZB/W F1 mice with a TIGIT-Ig fusion protein inhibited production of anti-double-stranded-DNA antibodies, delayed the development of proteinuria and prolonged survival in comparison with mice treated with control IgG. The TIGIT-Ig fusion protein demonstrated IgG-like stability similar to that of CTLA-4-Ig.