,19,20,40,41 In contrast to the above approach, we applied a data-driven clustering to identify COPD subtypes, which provides unbiased insights into COPD pathogenesis by identifying specific immune cell populations (e.g., activated dendritic cells and macrophages, CD8+ T cells, and mast cells) that are enriched in lungs with a severe emphysema phenotype and correlate with disease severity. This evidence concerns the gene CD8A and pulmonary emphysema.