Abstract: SA-PO527

Monoclonal IgG Deposits on Tubular Basement Membrane in Renal Allograft: Is This Significant for Chronic Allograft Injury?

Session Information

Category: Transplantation

  • 1702 Transplantation: Clinical and Translational

Authors

  • Sawada, Anri, Tokyo Women's Medical University, Shinjuku-ku, Japan
  • Hattori, Motoshi, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Tanabe, Kazunari, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Koike, Junki, St.Marianna University, Kawasaki, Kanagawa, Japan
  • Nagashima, Yoji, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Nitta, Kosaku, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Kawanishi, Kunio, University of California, San Diego, La Jolla, California, United States
  • Taneda, Sekiko, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Okumi, Masayoshi, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Omoto, Kazuya, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Shimizu, Tomokazu, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Ishida, Hideki, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Honda, Kazuho, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan
  • Fuchinoue, Shohei, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
Background

In renal allografts, tubular basement membrane immune deposit (TBMID) has often been observed. Such deposits are usually found in association with BK virus nephropathy and immune complex glomerulonephritis; however, their significance is not well-understood. In recent years, monoclonal immunoglobulin (Ig) G deposition in the glomeruli has been reported. However, monoclonal IgG TBMID has not been studied until now. Therefore, we conducted a retrospective clinicopathological study on monoclonal IgG TBMID.

Methods

In total, 7177 biopsy specimens obtained in our institution from 2007 to 2015 were studied. Conventional light and electron microscopic studies and indirect fluorescence immunostaining for Ig heavy and light chains and complements C1q and C3c were performed. Monoclonal IgG TBMID was diagnosed if an IgG subclass or light-chain restriction was present and all other antibodies were absent in TBMID.

Results

Ten patients showed monoclonal IgG TBMID. Of these, seven showed monoclonal IgG1κ TBMID and three showed monoclonal IgG2κ, IgG2λ, and IgG3κ TBMID, respectively. In all patients with monoclonal IgG1κ TBMID, abundant and large granular electron-dense deposits (EDD) were detected in the tubular basement membrane (TBM). EDD was absent in TBM in patients with monoclonal IgG2κ, IgG2λ, and IgG3κ TBMID. On the other hand, eight patients showed polyclonal IgG TBMID. Progression of interstitial fibrosis and tubular atrophy (IFTA) was significantly higher in patients with monoclonal IgG and IgG1κ TBMID compared with that in those with polyclonal IgG TBMID (P < 0.05). There were no significant differences in the other clinical parameters between monoclonal IgG and IgG1κ and polyclonal IgG TBMID.

Conclusion

This is the first study on patients with monoclonal IgG TBMID in renal allografts. We found that monoclonal IgG1κ TBMID was associated with EDD formation in TBM and the progression of IFTA.