Two recent studies reported activation of plasmacytoid dendritic cells (pDCs) by complexes between NETs and antimicrobial peptides such as LL-37 that engage Toll-like receptor 9 (TLR9) and result in Type I interferon production, a process known to be associated with SLE [5,6]. Here, TLR9 is linked to systemic lupus erythematosus.