TIGIT and graft versus host disease: [4] In line with this finding, Levin et al. showed that TIGIT overexpression reduces the development of EAE. [3] Furthermore, soluble TIGIT inhibits collagen-induced arthritis by dampening CD4+ T cell responses and by interfering with CD226-mediated costimulation. Additionally, blocking TIGIT accelerated mortality in a mouse model of graft versus host disease [3].