We demonstrated that anti‐PD1 antibody treatment can activate the immune‐killing function of CD8+ MAIT cells in patients with NSCLC and COPD, and responsiveness to immunotherapy is related to the distribution of MAIT‐17 and MAIT‐IFNγ‐R cell subclusters. The gene discussed is IFNGR1; the disease is chronic obstructive pulmonary disease.