IgG4-related Kidney Disease Mimicking Malignant Ureter Tumor: Case Report and Literature Review

Immunoglobulin G4-related disease is a recently recognized systemic disease that can affect any organ or tissue in the body, including the kidneys. IgG4-related kidney disease (IgG4-RKD) is an important part of immunoglobulin G4-related disease. The most common renal manifestation of IgG4-RKD is tubulointerstitial nephritis and glomerular lesions. There, however, is few case of IgG4-RKD mimicking malignant ureter tumor leading to severe hydronephrosis. We herein report an unusual case of IgG4-RKD mimicking malignancy.A 66-year-old Asian man presented to the nephrologist with soreness of loins, anorexia, and acute kidney injury in 2010. His renal function spontaneously improved after 2 weeks' hemodialysis without systemic steroid therapy. Four years later, he presented to the urologist with severe left hydronephrosis because of marked thickness of the left ureter wall. As a ureteral malignancy could not be ruled out, laparoscopic nephroureterectomy was performed.IgG4-related kidney disease was confirmed by the histologic examination. Then, repeat laboratory test showed almost complete recovery of renal function after initiation of steroidal therapy.This case highlights the rare possibility of IgG4-RKD mimicking malignant ureter tumor. Nephrologist and pathologists should be aware of the possibility that hydronephrosis with ureter obstruction may be involved in IgG4-RKD.

Acute Tubulointerstitial Nephritis Associated with Infliximab in a Patient with Crohn's Disease

We report the findings of a 46-year-old man, who presented with fever and renal dysfunction while undergoing treatment for Crohn's disease with infliximab (IFX). Remittent fever and renal dysfunction with urinary casts developed and lasted for 3 weeks without deterioration of Crohn's disease. Renal biopsy revealed acute tubulointerstitial nephritis (ATIN). After the discontinuation of IFX, his fever and renal abnormalities resolved. We herein report the first known case of ATIN associated with IFX.

Pentraxin 3 Is Closely Associated With Tubulointerstitial Injury in Lupus Nephritis: A Large Multicenter Cross-Sectional Study

Lupus nephritis always elicits immune inflammatory tissue damages in kidney. Pentraxin 3 (PTX3), mainly produced at inflammatory sites, is known to be involved in the regulation of the innate immunity system. The aim of this study was to investigate the serum and urine levels of PTX3, and the expression of PTX3 in renal tissues in lupus nephritis patients from a large Chinese cohort.The study used cross-sectional survey and 288 active lupus nephritis patients, including discovery cohort and validation cohort, 115 systemic lupus erythematosus (SLE) patients without clinical renal involvement and 46 healthy controls were enrolled. Serum and urine PTX3 were screened by enzyme-linked immunosorbent assay (ELISA). The renal deposition of PTX3 was detected by immunohistochemistry and immunofluorescence.The average level of serum PTX3 in the discovery cohort of lupus nephritis was significantly higher than that in nonrenal involvement SLE group and normal controls (P < 0.001, P < 0.001, respectively), which was confirmed by the validation cohort. Serum PTX3 levels of 15 lupus nephritis patients in remission decreased significantly compared with that in active phase. Serum PTX3 levels were significantly higher in patients with hematuria (P = 0.014), leucocyturia (P = 0.002), acute renal failure (P = 0.001), and nephrotic syndrome (P = 0.036). There were significant correlations between serum PTX3 levels and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, serum creatinine value, renal pathological activity indices, and serum complement 3 (C3) in active lupus nephritis patients. The urinary PTX3 levels were significantly higher in active lupus nephritis patients compared with patients in remission and normal controls (P = 0.011, P = 0.008, respectively). There were significant associations between urinary PTX3 levels and multiple indices of tubulointerstitial lesions, including urinary KIM-1 (r = 0.368, P = 0.016), neutrophil gelatinase-associated lipocalin (NGAL) (r = 0.320, P = 0.039), microalbumin (r = 0.621, P = 0.003), transferring (r = 0.451, P = 0.040) levels and renal pathological indices scores, especially interstitial inflammation (r = 0.349, P = 0.025) in active lupus nephritis patients. A significant correlation was found between serum and urine PTX3 levels (r = 0.431, P = 0.006). PTX3 staining was mainly observed in tubulointerstitial areas of patients with lupus nephritis, and immunofluorescence study showed that PTX3 could colocalize with fibroblast in interstitium.Circulating and local PTX3 levels were significantly increased in patients with active lupus nephritis and might be a biomarker for the disease progression, especially of tubulointerstitial injury.

Reduced NOV/CCN3 Expression Limits Inflammation and Interstitial Renal Fibrosis after Obstructive Nephropathy in Mice

The main hallmark of chronic kidney disease (CKD) is excessive inflammation leading to interstitial tissue fibrosis. It has been recently reported that NOV/CCN3 could be involved in kidney damage but its role in the progression of nephropathies is poorly known. NOV/CCN3 is a secreted multifunctional protein belonging to the CCN family involved in different physiological and pathological processes such as angiogenesis, inflammation and cancers. The purpose of our study was to determine the role of NOV/CCN3 in renal inflammation and fibrosis related to primitive tubulointerstitial injury. After unilateral ureteral obstruction (UUO), renal histology and real-time PCR were performed in NOV/CCN3-/- and wild type mice. NOV/CCN3 mRNA expression was increased in the obstructed kidneys in the early stages of the obstructive nephropathy. Interestingly, plasmatic levels of NOV/CCN3 were strongly induced after 7 days of UUO and the injection of recombinant NOV/CCN3 protein in healthy mice significantly increased CCL2 mRNA levels. Furthermore, after 7 days of UUO NOV/CCN3-/- mice displayed reduced proinflammatory cytokines and adhesion markers expression leading to restricted accumulation of interstitial monocytes, in comparison with their wild type littermates. Consequently, in NOV/CCN3-/- mice interstitial renal fibrosis was blunted after 15 days of UUO. In agreement with our experimental data, NOV/CCN3 expression was highly increased in biopsies of patients with tubulointerstitial nephritis. Thus, the inhibition of NOV/CCN3 may represent a novel target for the progression of renal diseases.

The Pathogenesis and Therapeutic Implications of Tubulointerstitial Inflammation in Human Lupus Nephritis

Nephritis is a common complication of systemic lupus erythematosus for which current therapies often prove inadequate. Current lupus nephritis classification systems emphasize glomerular acuity and scarring. However, tubulointerstitial inflammation (TII) and scarring are much better predictors of progression to renal failure. It now is becoming clear that the immunologic features, and probable underlying mechanisms, are very different in lupus glomerulonephritis and TII at the time of biopsy. Although glomerulonephritis is a manifestation of systemic autoimmunity, TII is associated with local in situ adaptive immune cell networks predicted to amplify local inflammation and tissue damage. In addition, poorly defined networks of innate immune cells and effectors likely contribute to the severity of local inflammation. Defining these in situ immune mechanisms should lead to a better understanding of prognostically meaningful lupus nephritis subsets and show novel therapeutic opportunities.

Clinicopathological significance of CD206-positive macrophages in patients with acute tubulointerstitial disease

OBJECTIVE

To investigate the clinicopathological significance of CD206-positive macrophage expression in patients with acute tubulointerstitial disease, including acute tubular necrosis (ATN) and acute interstitial nephritis (AIN).

METHODS

Renal tissue samples from patients with ATN (n=10), AIN (n=10), and minimal change disease (MCD, as disease control, n=8) as well as tissue from normal control kidneys (negative control, n=3) were included in this study. The expression of CD206 and CD68 in renal tissues was detected by immunohistochemistry or immunofluorescence.

RESULTS

CD206-positive cells accumulated in areas around damaged tubular cells and regenerating tubules. Compared with AIN patients, ATN patients had lower serum albumin, lower proteinuria, lower urinary osmolality and higher plasma hemoglobin, (P=0.002; P=0.01; P<0.001; P=0.002, respectively). CD206-positive cells could also be observed in the tubular basement membrane and tubule lumen. Some CD206-positive cells infiltrated into the tubular cells in patients with AIN. Compared to patients with ATN, patients with AIN had more CD206-positive cells (P=0.005). In the ATN patients, there were more CD206-positive cells in ischemic tissue. CD206-positive cells were negatively correlated with hemoglobin (r=-0.565, P=0.009) and positively correlated with serum albumin (r=0.496, P=0.026), urinary osmolality (r=0.567, P=0.009) and proteinuria (r=0.460, P=0.041). There was no correlation between CD206-positive cells and eGFR.

CONCLUSION

CD206-positive macrophages are involved in the pathogenesis of acute tubular necrosis and acute interstitial nephritis.

Acute tubulointerstitial nephritis in Scotland

BACKGROUND AND AIMS

Acute tubulointerstitial nephritis (ATIN) is a potentially reversible cause of acute kidney injury with the majority of cases drug related. Our aims were to examine the incidence profile of patients with ATIN in Scotland and to assess the impact of corticosteroid treatment.

DESIGN AND METHODS

All adult patients with biopsy-proven ATIN, diagnosed between 2000 and 2012, presenting to renal units serving 1.9 of Scotland's 5 million population were included. Patient demographics, presenting, aetiologic and pathologic features, treatment given and outcome were extracted from patient records.

RESULTS

In total, 171 cases representing 4.7% of native renal biopsies were identified. Median serum creatinine (sCr) was 327 μmol/l at biopsy (106 μmol/l at baseline). Eosinophilia, fever or rash was present in 57% with all 3 in only 1.1%. Active urinary sediment was found in 68%. Aetiology appeared drug induced in 73%. Proton pump inhibitors (PPIs) were likely causative in almost as many cases as antibiotics (35% each) and were more frequently implicated than non-steroidal anti-inflammatory drugs (20%). Number of PPI-related cases paralleled the rising prescription of these drugs. Corticosteroids were prescribed in 59% of drug-induced ATIN (median sCr at biopsy: 356 μmol/l vs. 280 μmol/l in those managed conservatively). There was no difference in sCr at 1, 6 and 12 months, with similar proportions of both groups experiencing complete renal recovery (48% vs. 41%) and becoming dialysis dependent (10% in both).

CONCLUSIONS

Incidence of biopsy-proven ATIN in Scotland has been rising over the past decade with the majority of cases drug induced. Evidence supporting corticosteroid treatment is lacking.

Immunologically mediated drug-induced acute renal failure

(1) AIN is the most frequent pattern of drug-induced immunologically mediated renal injury. A number of drugs may be responsible for AIN, namely methicillin and other penicillin derivatives, rifampicin, phenindione and sulfonamides. Particular clinical and pathological features often suggest an immune pathogenetic mechanism. IgG anti-TBM and IgE antibodies have been found in only a few cases and it is likely that antibody-mediated and cell-mediated injury may operate in the same patient. (2) Only few examples of drug-induced vasculitis and glomerulonephritis are known, and the pathophysiology of this kind of renal damage is poorly understood.

Immunologically mediated tubulo-interstitial nephritis in children

14 children with proven or presumably immunologically mediated tubulo-interstitial nephritis are presented. In 2 patients anti-tubular basement membrane antibodies were detected. In 6 immunofluorescence microscopy showed granular deposits of immunoglobulin and/or complement likely representing interstitial location of immune complexes. The findings by immunofluorescence were not significant in the remaining 6 patients. However, the association of renal disease to extra-renal disorders, namely chronic active hepatitis and ulcerative colitis, or uveitis or the presence of an epithelioid granuloma with multinucleated giant cells suggests that in such patients an immunologic disorder might be responsible for the tubulo-interstitial nephritis.

The role of the interstitium of the renal cortex in renal disease

Morphometrical investigations (point-counting method) showed that in different inflammatory (endocapillary -- acute -- GN, mesangioproliferative GN, membranoproliferative GN) glomerulonephritides and in non-inflammatory glomerular diseases (perireticular amyloidosis), there are statistically significant correlation between serum creatine concentrations at the time of biopsy and the enlargement of the cortical interstitium by fibrosis. Similar results were obtained in investigating different grades of benign nephrosclerosis with transition into secondary malignant nephrosclerosis conditioned by hypertension and in chronic diffuse sclerosing interstitial nephritides of different etiologies. As hypothesis, we assume that a narrowing of the postglomerular vessel network by interstitial fibrosis take place. This could lead to an increase resistance of the renal cortical blood flow. In spite of an elevated effective filtration pressure, the slowing of the glomerular blood flow may lead to the reduction of GRF and to an increase of the serum creatinine concentration. Additionally, in the case of interstitial fibrosis the tubules look atrophied. This could be the consequence of the reduced GFR as a sign of inactivity. On the other hand, tubular atrophy could result from malnutrition in the case of interstitial fibrosis. The resorptive capacity of these atrophied-looking tubules could be lowered and the GFR could be diminished by the so-called Thurau mechanism.

Interstitial nephritis

There are many causes of interstitial nephritis other than pyelonephritis. The term interstitial nephritis does not connote a single etiologic or pathogenetic mechanism; it rather arbitrarily places together a wider variety of renal diseases that have a predilection for early and major involvement of the renal interstitium. The prototype of acute interstitial nephritis is acute pyelonephritis. In addition, there is a drug-related acute interstitial disease that is probably of immunological nature and usually reverses with discontinuance of the offending drug. Chronic interstitial nephritis includes many diverse illnesses. Nonobstructive pyelonephritis occurs but its prevalence is debated. Analgesic abuse nephropathy is not rare and is potentially reversible. Papillary necrosis has many causes and a wide spectrum of clinical presentations. Heavy metals, such as lead, cause interstitial nephritis. Balkan nephropathy occurs in an endemic area and although not bacterial in origin is of unknown cause.

Synovitis in a Patient with IgG4-related Disease

A 71-year-old man was admitted to our department due to arthralgia and renal dysfunction. A physical examination disclosed swelling of the right shoulder and left wrist joints. Laboratory tests showed elevated serum IgG4 and creatinine levels, and magnetic resonance imaging of the wrist revealed bone erosion and synovitis. In addition, fluorodeoxyglucose positron emission tomography showed uptake in the submandibular glands, pancreas, kidneys, and affected joints and a renal biopsy revealed tubulointerstitial nephritis with the infiltration of IgG4+ plasma cells. The patient was subsequently diagnosed with IgG4-related disease (IgG4-RD) and successfully treated with corticosteroid therapy. This case suggests that erosive arthritis may occur in patients with IgG4-RD.

Megalocytic interstitial nephritis following acute pyelonephritis with Escherichia coli bacteremia: a case report

Megalocytic interstitial nephritis is a rare form of kidney disease caused by chronic inflammation. We report a case of megalocytic interstitial nephritis occurring in a 45-yrold woman who presented with oliguric acute kidney injury and acute pyelonephritis accompanied by Escherichia coli bacteremia. Her renal function was not recovered despite adequate duration of susceptible antibiotic treatment, accompanied by negative conversion of bacteremia and bacteriuria. Kidney biopsy revealed an infiltration of numerous histiocytes without Michaelis-Gutmann bodies. The patient's renal function was markedly improved after short-term treatment with high-dose steroid.

[Successful steroid therapy for indolent myeloma with kidney injury due to direct infiltration of myeloma cells]

A 68-year-old woman visited JA Toride Medical Center with asymptomatic proteinuria. Bence Jones protein-λ was identified in her serum and urine samples, and subsequent bone marrow aspiration revealed multiple myeloma (MM). Simultaneous renal biopsy showed only minor glomerular abnormality and preserved interstitium. Since the clinical stage was not advanced, aggressive treatment was avoided. During the following six months, her renal function gradually deteriorated with sustained elevation of urine protein and β2 microglobulin excretion, although other routine blood tests yielded stable results. In contrast to the first renal biopsy, the second biopsy specimen exhibited findings suggestive of inflammatory cell infiltration associated with light chain deposition along the tubular basement membrane. However, her myeloma did not cause symptoms other than mild renal disorder and remained in the category of indolent myeloma. Therefore a moderate dose of steroid therapy according to the regimen of common interstitial nephritis was initiated and her renal function and urinary findings partially recovered. Subsequently, her condition was diagnosed as infiltration of plasma cells with positive λ-light chain deposition. Since direct infiltration of myeloma cells into the renal interstitium rarely causes renal failure especially at the initial stage, we did not conduct intensive chemotherapy with possible severe side effects. More intensive chemotherapy would have been administered if the patient had suffered from other organ damage. There are no reports of cases in whom steroid alone was effective against multiple myeloma, hence this case is of clinical significance in providing a treatment option for renal dysfunction caused by restricted infiltration of myeloma cells, especially for cases where intensive chemotherapy is contraindicated.

Drug-induced acute interstitial nephritis: pathology, pathogenesis, and treatment

Drug-induced acute interstitial nephritis (DAIN) is a common cause of acute kidney injury and often presents as an unexplained rise in serum creatinine level. Kidney biopsy is therefore frequently required to make a definitive diagnosis. The hallmark pathologic features of DAIN are interstitial edema, interstitial inflammation, and tubulitis with a predominance of CD4+ T lymphocytes and mononuclear cells, with variable numbers of eosinophils. This is a result of a type B idiosyncratic non-immunoglobulin-E-mediated immune reaction marked by cell-mediated immune injury to the renal tubulointerstitium. The drug becomes immunogenic via various mechanisms such as haptenization, antigen mimicry, and neo-antigen formation. Renal interstitial dendritic cells, and renal tubular epithelial cells play an important role in further propagating this immunologic injury. Acute DAIN can progress within days to weeks to a chronic form triggered by fibroblast activation and manifested as interstitial fibrosis and tubular atrophy. The mainstay of treatment of DAIN is discontinuation of the offending drug. Incomplete renal recovery is seen in one-third of the patients and depends on the duration of injury prior to diagnosis. Use of steroids for treatment of DAIN makes biological sense, but lack of randomized controlled trials and conflicting data from retrospective studies makes the approach unclear. Positive effects include faster recovery of kidney function, more complete recovery with less chronic kidney disease, and reduced need for chronic dialysis. Therefore, it seems reasonable to employ corticosteroids in patients that do not rapidly improve 3 to 5 days following discontinuation of the offending agent.

Tubulointerstitial Nephritis Caused by Peritubular Capillaritis Accompanied by Cryoglobulinemia

A 73-year-old man with fever, renal insufficiency, and purpura was referred to our hospital to be evaluated for renal insufficiency. Renal biopsy revealed acute and chronic tubulointerstitial nephritis with no laboratory findings of sarcoidosis or connective tissue disease. Low C4 levels and elevation of rheumatoid factors suggested cryoglobulinemia, which was confirmed with quantitative analysis. CD34 staining of kidney tissue revealed peritubular capillaritis. Antineutrophil cytoplasmic antibodies were negative. The etiology of peritubular capillaritis was not clear in our patient; however, it might be associated with cryoglobulinemia because we cannot find any other diseases that could have induced the peritubular capillaritis.

[Case of a 14-year-old boy with chronic tubulointerstitial nephritis first diagnosed as acute focal bacterial nephritis]

A 14-year-old boy was admitted to a general hospital because of prolonged fever of unknown origin. After Enterococcus feacalis was detected from his urine and abdominal contrast enhanced computed tomography and 99m-Tc dimercaptosuccinic acid scintigram showed multiple focal defects, he was diagnosed as acute focal bacterial nephritis (AFBN). His condition recovered as a result of Ampicillin (ABPC)and Cefotaxime infusion. There was no specific finding in voiding cystography. Six months later, his fever recurred and he was diagnosed as refractory AFBN because Enterococcus feacalis was detected in his urine again. He was treated with ABPC and Meropenem (MEPM) infusion, but the fever persisted and his renal function deteriorated. He was transferred to our hospital for intensive treatment. On admission, blood examination showed findings of inflammation (WBC 14,400/μL, CRP 3.7 mg/dL, erythrocyte sedimentation rate : 69 mm/h, IgG : 2,107 mg/dL) and renal impairment (Cr : 1.8 mg/dL, cystatin C : 2.0 mg/L). Although neither pyuria nor pathogenic bacteria were detected in his urine, Enterococcusfeacalis was detected at the hospital where he had been treated previously, hence we started treatment for AFBN with ABPC, MEPM, Levofloxacin, then Linezolid. However, the fever persisted and his renal function deteriorated (Cr 2.0 mg/dL). Kidney-specific accumulation was found in Ga scintigraphy, which suggested chronic inflammation. Clinical course and laboratory findings showed no symptoms of bacterial, viral, fungal, or tuberculous infections nor collagen disease. Although renal biopsy revealed no glomerular abnormality, tubulointerstitial edema, fibrosis and tubulitis were observed. Rupture of the tubular basal membrane and non-caseating granulomas also existed. Pathological findings did not match those of renal sarcoidosis. Ophthalmological screening negated the existence of tubulointerstitial nephritis with uveitis syndrome. After methylprednisolone pulse therapy, the fever recovered immediately and his renal impairment imroved gradually (Cr 1.49 mg/dL). He continues to undergo treatment as an outpatient. Although tubulointerstitial nephritis is rare in children, some patients have a poor renal prognosis. It is important to determine the existence of tubulointerstitial nephritis on treating a patient with renal impairment.

[Tubulointerstitial rejection of renal allografts]

Tubulo-intersticial rejection represents T-cell mediated rejection of kidney allografts with the morphology of immune-mediated interstitial nephritis. Diagnosis is dependent on the histopathological evaluation of a graft biopsy sample. The key morphological features are interstitial inflammatory infiltrate and damage to tubular epithelial cell which in severe cases can result in the ruptures of the tubular basement membranes. The differential diagnosis of tubulo-interstitial rejection includes acute interstitial nephritis and viral inflammatory kidney diseases, mainly polyomavirus nephropathy.

Ultrastructural studies of IgG4-related kidney disease

OBJECTIVE

Ultrastructural studies of IgG4-related kidney disease (IgG4-RKD) characterized by tubulointerstitial nephritis (TIN) are limited in previous reports due to the rarity of the condition. In the present report, we performed ultrastructural examinations and assessed the pathogenesis of this disease.

PATIENTS

Clinicopathological studies were conducted in eight patients diagnosed with IgG4-RKD. Routine light, immunofluorescence and electron microscopy examinations and immunohistochemical assessments of IgG4 were performed using renal biopsy samples.

RESULTS

Hypocomplementemia, positive anti-nuclear antibodies and eosinophilia were confirmed in more than half of the cases. Electron dense deposits (EDDs) were frequently found in the glomeruli and interstitium. The rate of deposition was 62.5% in both mesangial areas and Bowman's capsule. EDDs were frequently detected on the tubular basement membrane (TBM) (87.5% of patients). The interstitium also contained EDDs on collagen fibers in 87.5% of the cases and on basement membrane-like materials in areas of fibrosis in 37.5% of the cases. The creatinine clearance levels were significantly lower in the patients with the latter pattern. Meanwhile, the rate of immunoglobulin and/or complement deposition on the TBM was observed in less than 37.5% of patients, and these findings were not entirely coincident with the cases of EDDs on the TBM.

CONCLUSION

EDDs are frequently found in the glomeruli and interstitium in patients with IgG4-RKD; however, immunohistological studies do not provide evidence that IgG4-RKD involves TIN with immune complex nephropathy. The presence of interstitial EDDs may be related to the progression of interstitial fibrosis in the setting of IgG4-RKD.

Vimentin is a dominant target of in situ humoral immunity in human lupus tubulointerstitial nephritis

OBJECTIVE

In lupus nephritis (LN), severe tubulointerstitial inflammation (TII) predicts progression to renal failure. Severe TII is associated with tertiary lymphoid neogenesis and in situ antigen-driven clonal B cell selection. The autoantigen(s) driving in situ B cell selection in TII are not known. This study was undertaken to identify the dominant driving autoantigen(s).

METHODS

Single CD38+ or Ki-67+ B cells were laser captured from 7 biopsy specimens that were diagnostic for LN. Eighteen clonally expanded immunoglobulin heavy- and light-chain variable region pairs were cloned and expressed as monoclonal antibodies. Seven more antibodies were cloned from flow-sorted CD38+ cells from an eighth biopsy specimen. Antigen characterization was performed using a combination of confocal microscopy, enzyme-linked immunosorbent assay, screening protoarrays, immunoprecipitation, and mass spectrometry. Serum IgG titers to the dominant antigen in 48 LN and 35 non-nephritic lupus samples were determined using purified antigen-coated arrays. Autoantigen expression on normal and LN kidney was localized by immunohistochemistry and immunofluorescence.

RESULTS

Eleven of 25 antibodies reacted with cytoplasmic structures, 4 reacted with nuclei, and none reacted with double-stranded DNA. Vimentin was the only autoantigen identified by both mass spectrometry and protoarray. Ten of the 11 anticytoplasmic TII antibodies directly bound vimentin. Vimentin was highly expressed by tubulointerstitial inflammatory cells, and the TII antibodies tested preferentially bound inflamed tubulointerstitium. Finally, high titers of serum antivimentin antibodies were associated with severe TII (P = 0.0001).

CONCLUSION

Vimentin, an antigenic feature of inflammation, is a dominant autoantigen targeted in situ in LN TII. This adaptive autoimmune response likely feeds forward to worsen TII and renal damage.

Tubulointerstitial nephritis accompanying gamma-heavy chain deposition and gamma-heavy chain restricted plasma cells in the kidney

Monoclonal immunoglobulin heavy chain (HC) diseases are rare proliferative disorders of B lymphocytes or plasma cells characterized by the presence of monoclonal α-, µ-, or γ-HC without associated light chains in the blood, urine, or both. We report a 59-year-old woman with a history of Hodgkin disease who developed hypercalcemia, proteinuria, and impaired kidney function. Protein electrophoresis and immunofixation displayed γ-HC without associated light chains in the serum and urine. Pathologic examination demonstrated severe tubulointerstitial nephritis associated with diffuse and strong linear staining of the glomerular and tubular basement membranes as well as Bowman capsules for γ-HC, but not for κ- or λ-light chains. Immunohistochemical examination of the kidney and bone marrow demonstrated numerous CD138+ plasma cells immunoreactive for γ-HC, but not for κ- or λ-light chains. This is the first report of tubulointerstitial nephritis associated with γ-HC deposition and γ-HC restricted plasma cells in the kidney. This report heightens awareness about tubulointerstitial nephritis as a possible manifestation of γ-HC deposition in the kidney.