Specifically, our findings support the notion that the restricted sulfur intake largely underlies MR-induced impairment of antitumour immunity, as dietary supplementation of a H2S donor or l-cysteine, a sulfur amino acid acting downstream of SAM, rescued dietary MR-induced resistance to anti-PD-1 treatment in immunocompetent mice but not in immunodeficient mice. The gene discussed is PDCD1; the disease is miotic rate.