CD8A and chronic obstructive pulmonary disease: Compared with the COPD rats treated with NAC + oe-VWF + sh-NC, the ratio of CD3+, CD4+, CD8+ and CD4+/CD8+T lymphocytes reduced in serum of COPD rats treated with NAC + oe-VWF + sh-p38 MAPK (Fig. 6B).