IFNA1 and pulmonary fibrosis: Some of the subsets we identified had very similar gene expression patterns to previously reported alveolar macrophage subsets in healthy participants (“Metallothionein Macrophages” – BAL Cluster 8)8,17, patients with severe COVID-19 (“IFN-Related Macrophages” – BAL Cluster 5)9–11, or patients with idiopathic pulmonary fibrosis (“Matricellular Macrophages” – BAL Cluster 6)14,15 (Table S6 summarizes published datasets compared with our dataset).