High levels of Treg cells contribute to the control of lung inflammation, maintaining local immune homeostasis and ultimately inhibiting the development of COPD.[28] Herein, we found that Activated & resting Treg and Activated & secreting Treg increased the risk of LUAD, which was confirmed by previous research: Treg cells promoted the progression and metastasis of LUAD by inhibiting CD8 + T cell-mediated anti-tumor immunity. The gene discussed is CD8A; the disease is neoplasm.