Although tubulointerstitial nephritis with IgG4+ plasma cell (PC) infiltration is a hallmark of IgG4-related kidney disease (IgG4-RKD), only a few studies are available about the minimum number of IgG4+PC needed for diagnosis along with IgG4+/IgG+PC ratio in the kidney. In addition, the significance of the deposition of IgG or complement as a reflection of humoral immunity involvement is still uncertain. In this study, we analyzed 20 Japanese patients with IgG4-RKD to evaluate the number of IgG4+PCs along with IgG4+/IgG+PC ratio and involvement of humoral immunity. The average number of IgG4+PCs was 43.8/hpf and the average IgG4+/IgG+ or IgG4+/CD138+ ratio was 53. IgG and C3 granular deposits on the tubular basement membrane (TBM) were detected by immunofluorescence microscopy in 13 and 47 of patients, respectively. Nine patients had a variety of glomerular lesions, and 7 of them had immunoglobulin or complement deposition in the glomerulus. In conclusion, we confirmed that infiltrating IgG4+PCs 10/hpf and/or IgG4/IgG (CD138)+PCs 40 was appropriate as an item of the diagnostic criteria for IgG4-RKD. A relatively high frequency of diverse glomerular lesions with immunoglobulin or complement deposits and deposits in TBM may be evidence of immune complex involvement in IgG4-related disease. (copyright) 2012 Mitsuhiro Kawano et al.
M., K., I., M., Y., Y., N., I., H., N., S., N., … T., S. (2012). Immunohistochemical Characteristics of IgG4-Related Tubulointerstitial Nephritis: Detailed Analysis of 20 Japanese Cases. International Journal of Rheumatology, 2012. Retrieved from http://www.embase.com/search/results?subaction=viewrecord&from=export&id=L365438157