TREM2 and idiopathic pulmonary fibrosis: To place this CD206hi macrophages cluster in the context of known macrophage subclusters in IPF, we re-interrogated the transcriptome of the macrophages in Habermann’s dataset and identified the two established macrophage subsets found in single cell analysis of IPF lungs - the FABP4+ macrophages [purportedly resident alveolar macrophages24] and the pro-fibrogenic SPP1+TREM2+ macrophages8,24,25 (clusters 0 and 1 respectively in Fig. 6c).