The results of this meta-analysis demonstrated that vitamin D can reinvigorate the FEV1, as well as FEV1/FVC within COPD patients, increase serum 25(OH)D, CD3+, CD4+and CD4+/CD8+levels, and reduce CD8+and the number of acute exacerbations and CAT scores. This evidence concerns the gene CD4 and chronic obstructive pulmonary disease.