Sphingomonas/Sphingobium species, which contain glycolipid Ags, activate intestinal iNKT cells to produce cytokines in a CD1d-dependent manner (30), whereas intestinal microbe Bacteroides fragilis-derived glycolipid Ags inhibit iNKT cell activation through competitive binding with CD1d, resulting in protection against oxazolone-induced colitis (31). The gene discussed is CD1D; the disease is colitis.