Although patients with severe COVID-19 have been found to have a cytokine storm in peripheral blood and bronchoalveolar lavage fluid [32,33], in lung parenchyma we only identified a small number of cytokine genes with differently major transcript usage, including IL1B, IL2, IL6ST, IL34, CCL2, CCL7, CMTM8, CSPG5, PDGFA, and PDGFRL (Figs 3D and S4). Here, PDGFRL is linked to COVID-19.