To determine whether sulfatide-reactive type II NKT cells accumulate in the draining PLN during the onset of T1D, PLN-derived mononuclear cells isolated from NOD mice (aged 6–20 weeks) were stained with either sulfatide/CD1d- or αGalCer/CD1d-tetramers for the identification of type II and type I NKT cells, respectively. The gene discussed is CD1D; the disease is type 1 diabetes mellitus.