CD8A and chronic obstructive pulmonary disease: Animal experiments showed that QBPF could regulate T lymphocyte subsets, increase CD3+ and CD4+ T cells, decrease CD8+ T cells [33], and increase the proportion of CD4+CD25+Foxp3+ Treg cells in COPD rats [34]. Clinical trials indicated that QBPF combined with Montelukast could down-regulate Th17 expression and up-regulate CD4+CD25+Foxp3+ Treg expression in acute exacerbation of COPD (AECOPD) patients [35].