Research Article
[Retracted] Effect of Autoimmune Cell Therapy on Immune Cell Content in Patients with COPD: A Randomized Controlled Trial
Figure 1
The grouping scheme for COPD patients. Note: the grading standard was that FEV1 accounted for % of the expected value. Level 1: mild; level 2: moderate; level 3: severe; level 4: extremely severe.