CAT and tuberculosis: To verify whether Arg-1, iNOS, or ROS participated in the inhibition of NKT by MDSCs, we co-cultured WT NKT with MDSCs sorted from livers of TB (B16) mice at a 1:1 ratio in the absence or presence of specific inhibitors of Arg-1, ROS, or iNOS: nor-NOHA (1 mM), catalase (1,000 U/ml), or l-NIL (0.5 μM), respectively (32).