Cellular Heterogeneity of HTII-280–Labeled Epithelial Cells in Healthy and Fibrotic Human Lungs

Previous work demonstrated that in idiopathic pulmonary fibrosis (IPF), the representation of AT2 cells is markedly reduced, accompanied by an increased presence of airway epithelial populations such as basal cells, — and newly identified pathological states including KRT5⁺KRT17⁻ /aberrant basaloid cells AT2 cells have been implicated as a potential source of both hyperplastic basal cells and KRT5⁺KRT17⁻ cells in IPF, based on findings from ex vivo lineage studies. The in vitro organoid culture studies often rely on in vitro organoid cultures of AT2 cells, which are typically isolated using HTII-280—a monoclonal antibody widely assumed to specifically label human AT2 cells. However, if the isolated HTII-280 populations are heterogeneous or contaminated, these lineage relationships may need to be reconsidered. To directly investigate the cellular composition of HTII-280–labeled cells in both healthy and fibrotic lungs, we performed scRNA-seq on fluorescence-activated cell sorting (FACS)–purified epithelial cells from the same sample, separating HTII-280⁺ and HTII-280⁻ fractions. Each population was independently labeled with TotalSeq anti-human Hashtag antibodies, then pooled at a 1:1 ratio for scRNA-seq analysis. In total, we profiled HTII-280⁺ and HTII-280⁻ epithelial cells from two healthy donor distal lung samples, two fibrotic IPF explants, and one non-fibrotic IPF explant.