Glycolipid Ags derived from the intestinal microbe B. fragilis (called GSL-Bf717 or BfaGCs) inhibit iNKT cell activation through competitive binding of their sphinganine branches with CD1d, resulting in protection against oxazolone (Oxa)-induced colitis, an experimental model mimicking UC (41–43). The gene discussed is CD1D; the disease is colitis.