LAG-3 deficiency in B6.SJL mice results in higher susceptibility to Hg-induced autoimmunity.116 In addition, NOD mice deficient for LAG-3 display accelerated T1D with 100% incidence.117 Interestingly, the NOD LAG3−/− mice exhibit increased T-cell numbers and enhanced proliferation of T cells in the islets, suggesting an inhibitory role for LAG-3 on T cells. Here, LAG3 is linked to type 1 diabetes mellitus.