[1467] Quantitation of IgG4+ Plasma Cells in Tubulointerstitial Nephritis.

Donald C Houghton, Megan L Troxell. Oregon Health and Sciences University, Portland

Background: IgG4-related tubulointerstitial nephritis (IRTIN) is a sclerosing lymphoplasmacytic inflammatory disorder that may affect the kidney alone, or may be part of the multi-system disorder, IgG4-related systemic disease (IRSD). Auto-immune pancreatitis (AIP) is the most common lesion of IRSD. The active inflammatory lesion in IRTIN is characterized by the presence of numerous IgG4+ plasma cells (IgG4+PC), but the specificity of this finding has not been determined. In this study we investigated the prevalence of IgG4+PC in renal interstitial infiltrates.
Design: We examined all renal biopsy samples with active interstitial inflammation, regardless of principal diagnosis, from 1/1/09 through 6/1/10, to determine the presence and extent of IgG4+PC in the infiltrates (N=100). Two observers independently scored each case for the density and extent of infiltrates, the apparent proportion of plasma cells, the extent and density of CD138+ plasma cells, and the distribution and numbers of IgG4+PC in the infiltrate.
Results: 29 cases were negative for IgG4+PC and 63 had fewer than 2 per high power field (hpf). The highest numbers of IgG4+PC were seen in some cases of diabetic nephropathy (DN), idiopathic interstitial nephritis (IISN), diffuse lupus nephritis (DLN), membranous glomerulonephritis (MGN), and necrotizing glomerulonephritis (NGN), including pauci-immune lesions, and those with granular and linear immune deposits:

Table 1
Diagnosis# of IgG4+PC/hpf
DN3 32 
IISN32 11
DLN5   1
MGN43 1 
# of cases in diagnosis categories with numerous IgG4+PC

Three biopsies from patients with Sjogren's syndrome demonstrated 0.7, 2.5 and 3.0 IgG4+PC/hpf, and a biopsy in the setting of tubulointerstitial nephritis-uveitis syndrome (TINU) was negative for IgG4+PC. PC were prominent in all cases with more than 20 IgG4+PC. The numbers of IgG4+PC did not correlate with severity of fibrosis, or the presence or absence of eosinophils. By comparison, infiltrates in a 2005 biopsy of IRTIN demonstrated dense sclerosis and numerous eosinophils, and contained more than 200 IgG4+PC/hpf.
Conclusions: Infiltrates of numerous IgG4+PC's are rare in renal biopsies, regardless of the density and activity of the inflammation, but they may be seen in some non-IRTIN cases, particularly in NGN. It may be instructive to further investigate our cases with this finding: in MGN because of it's known association with IRTIN; in DN because it may develop as a complication of AIP; and in IISN to rule out previously unsuspected IRTIN.
Category: Kidney (does not include tumors)

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 246, Wednesday Afternoon


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