IGKV4-1 and COVID-19: Specifically, signatures of plasma cells (IGHG3, IGKC, IGHM, JCHAIN, IGHG2, IGKV4-1, IGLV3-1, IGHA1), activated fibroblasts (COL1A1, COL1A2, COL3A1), inflammatory cytokines (CXCL9, CCL18) and complement factors (C1QB, C1QC) dominated the DE genes for the COVID-19 lung sections (Fig. 4d, Additional file 7: Table S7).