Wang R, et al. - This study was designed to evaluate the role of complement system in patients with biopsy-proven IgG4 related kidney disease (IgG4-RKD). For this investigation, 40,429 renal biopsies from January 2010 to January 2018 were re-examined, and 17 subjects were confirmed to meet the criteria of IgG4-RKD. The data presented in this work showed the probably harmful role of complement activation in IgG4-RKD. The features of IgG4-RKD were substantial IgG4⁺ plasma cells infiltration and storiform fibrosis. Researchers found that IgG4-RKD was a relatively rare entity.