Polyclonal immunoglobulin G deposition on the tubular basement membrane in a diabetic nephropathy: A case report

A 70‐year‐old Japanese man with diabetes mellitus was referred to our hospital for treatment of renal dysfunction. Renal biopsy revealed that the tubular basement membrane (TBM) showed extreme thickening histologically, and selective polyclonal immunoglobulin G deposition on the thickened TBM, whereas no immunoglobulin deposition was found in the glomeruli in an immunofluorescence study. In electron microscopy, a powdery type of electron dense material, which was similar to that seen in Randall‐type monoclonal immunoglobulin deposition disease (MIDD), was observed on the tubular epithelial side of the TBM. However, the present case was differentiated from MIDD, because polyclonal deposition with both kappa and lambda deposition on the TBM was observed. Moreover, there was no noticeable glomerular deposition, which is usually found in cases of MIDD. Anti‐TBM disease was also considered as a differential diagnosis, in which polyclonal immunoglobulin deposits selectively on the TBM. However, in the present case, prominent interstitial nephritis was not observed. A similar case with a history of diabetes mellitus has been reported, which was diagnosed as Polyclonal Immunoglobulin G Deposition Disease. No further reports of this case have emerged thereafter; we present this case as the second report supporting this article.     

Relationship of tissue deposits of cryoglobulin to clinical features of mixed cryoglobulinemia

Two patients with type 2 mixed cryoglobulinemia had tissue deposits of serum cryoproteins. Patient 1, a 72-year-old man, had purpura and glomerulonephritis. The serum cryoglobulin consisted of monoclonal IgM kappa and polyclonal IgG. Renal biopsy revealed diffuse proliferative glomerulonephritis with abundant IgG, IgM, kappa light chain, and complement in glomerular capillary walls. These immunoglobulins, but no complement, were also present in histologically normal cutaneous blood vessels. Ultrastructurally, cutaneous vascular deposits were identical to the renal deposits and to the crystalline mixed IgM-IgG serum cryoprecipitates and renal deposits previously described. Patient 2 was a 68-year-old man with sensorimotor peripheral polyneuropathy and purpura. His serum cryoglobulin consisted of monoclonal IgA lambda and polyclonal IgG. Sural nerve and skin biopsies revealed vasculitis involving small arteries and arterioles. Immunoglobulin A and complement were present in perineurial arteriolar walls of the sural nerve. Cryoprecipitates in both cases had strong rheumatoid factor activity. These findings support the view that in type 2 cryoglobulinemia tissue deposits consist of cryoprotein immune complexes. The presence of these deposits in histologically normal blood vessels in patient 1 suggests that deposition of cryoproteins precedes and may initiate tissue damage.     

Isologous monoclonal antibodies can induce anti-GBM glomerulonephritis in rats.

Injection of isologous monoclonal antibodies (SR2, SR3) caused anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM nephritis) in WKY/NCrj rats. The antibodies were obtained from hybridoma cells derived from fusion of the spleen of a nephritic WKY/NCrj rat injected with rat solubilized renal basement membranes with adjuvant, and mouse SP2-myeloma cells. They belonged to the rat IgG2a subclass and bound to rat kidney in a linear pattern along the glomerular and tubular basement membranes. Histological changes in glomeruli were detected at day 1 after the injection; proteinuria with haematuria appeared on day 2; and proteinuria became severe and reached a plateau by day 5. These results demonstrate that anti-GBM nephritis can even be induced by an isologous monoclonal antibody and that the rat IgG2a subclass is at least nephritogenic. The experimental model of anti-GBM nephritis with isologous monoclonal antibodies makes it possible and easier to analyse further the mechanism of anti-GBM nephritis.     

Intramembranous fine deposit disease associated with collagen disorders: a new morphological entity?

Summary A distinct, hitherto unknown renal histopathological appearance, consisting of diffuse thickening of the glomerular basement membrane (GBM) with fine intramembranous electron-dense deposits, was observed in the renal biopsies from three patients with collagen diseases. In each case, proteinuria was mild with normal urinary sediment. On light microscopy there were no particular abnormalities but a mild thickening of the glomerular capillary wall. Immunofluorescence studies revealed faint linear or extremely fine granular IgG deposition along the capillary wall. On electron microscopy, the GBM was diffusely thickened with fine intramembranous electron-dense deposits without spike formation. No other deposits were seen in the glomerulus. These histological features resembled those of membranous glomerulonephritis (MGN), although the possibility of the early change of MGN is excluded by specific findings in these cases. Other GBM-thickening diseases such as diabetic glomerulosclerosis were ruled out clinically and histologically. Our cases have a singular renal histopathology which differs from any of the previously established classifications of glomerular lesions. It may be a specific change associated with some type of collagen disease.     

Ultrastructural Changes of Tubular Basement Membranes in Immunologic Renal Tubular Lesions in Humans

Ultrastmctural changes in the tubular basement membrane (TBM) of 65 renal biopsy specimens from patients with nephropathies or transplant rejection were examined for their potential relationship to deposits observed along the TBM by immu nofluorescence (IF). The TBM showed various alterations: irregularities with thickening, lamella tion, duplication, and clear spaces. Granular vesicles or inclusions were present inside the thickened TBM. The morphologic changes of the TBM occurred regardless of the severity of rejection of transplants and the type of deposits observed on IF. Electron-dense deposits inside or along the TBM were not found in cases of linear deposits, however. Although these changes were not strictly specific to tubular immune diseases, they could reflect a reaction of the TBM to immune complexes or deposits of antibodies to TBM with degeneration of tubular epithelial cells and sometimes regeneration of a new TBM.     

Polyvalent antigen-antibody interactions are required for the formation of electron-dense immune deposits in passive Heymann''s nephritis.

In order to analyze the initial steps involved in the formation of subepithelial electron-dense immune deposits, the authors induced passive Heymann's nephritis in rats by intravenous injection of monoclonal or polyclonal antibodies to the relevant antigen, a 330,000-dalton brush border protein also expressed within coated pits of glomerular epithelial cells. Whereas both mono- and polyclonal antibodies induced deposits detectable by indirect immunofluorescence, electron-dense deposits were only found in glomerular capillary walls of rats injected with polyclonal antibodies. Immunoultrastructural analysis confirmed the subepithelial location of heterologous IgG: monoclonal antibodies were essentially confined to the coated pits of glomerular epithelial cells, whereas polyclonal antibodies were detected in coated pits and in the subepithelial electron-dense deposits. In the face of an excess of circulating antibody, gp 330 was not detectable in the deposits, but a striking increase in the number of endoplasmic reticula positive for gp 330 was found. The results indicate that highly cross-linked immune complexes formed by polyvalent antibodies on the epithelial cell surface are necessary for the induction of subepithelial electron-dense deposits.     

Glomerular and serum immunoglobulin G subclasses in membranous nephropathy and anti-glomerular basement membrane nephritis

The distribution of human IgG subclasses among the glomerular deposits of 53 patients with glomerulonephritis was examined by immunofluorescence (IF) with subclass-specific monoclonal antibodies (Mab). A subclass restriction was observed in idiopathic membranous nephropathy (MN) with glomerular deposits predominantly containing IgG4 (81% of the studied biopsies) and IgG1 (75%). In de novo MN, occurring after transplantation, the restriction was markedly different, with a predominance of IgG1 (100%) and IgG2 (69%). In anti-glomerular basement membrane (a-GBM) nephritis the restriction was considerable with deposits containing almost exclusively IgG₁ (91%) and IgG4 (73%). The same restriction was observed for circulating anti-GBM antibodies detected by indirect IF assay. By contrast IgG1, IgG2, and IgG3 deposits were identified in lupus proliferative glomerulonephritis. Serum IgG subclass levels were measured in 29 patients with idiopathic MN and a-GBM nephritis by an indirect competitive immunoenzymatic assay using Mab. Mean percentage of IgG₂ serum level was significantly lower in patients. In spite of high variations from patient to patient, a serum IgG subclass imbalance was clearly present in 10 cases with low IgG₂ and high IgG₁ and IgG₃ levels. The imbalance in these patients was not due to urinary loss since it was observed with a similar frequency in hypo- and normoimmunoglobulinemic patients. In 5 out of these 10 patients IgG₂ levels were very low, analogous to those observed in selective IgG₂ deficiency. Whether the important subclass restriction of glomerular IgG (in which patterns differed according to the type of glomerulonephritis) and the serum subclass imbalances were due to a clonally restricted antibody response to a particular antigen or to a host immune response defect, or both, remains to be elucidated.     

Comparison of polyclonal and monoclonal antibodies in determination of glomerular deposits of hepatitis B virus antigens in hepatitis B virus-associated glomerulonephritides

The nature of hepatitis B virus (HBV) antigens in HBV-associated glomerulonephritides was investigated in 7 hepatitis B surface antigen (HBsAg) carriers with membranous nephropathy, 16 HBsAg carriers with mesangial IgA nephropathy, and 1 HBsAg carrier with a mixed picture of membranous and IgA nephropathies. Consecutive frozen sections of renal biopsy specimens were stained with polyclonal and monoclonal antibodies against HBV antigens. Glomerular capillary deposits of HBeAg and HBcAg were detected in 66% and 57% of renal biopsies from HBsAg carriers with membranous nephropathy by monoclonal and polyclonal antibodies, respectively. The discrepancy in the immunofluorescence findings resulted from the cross-reactivity of the polyclonal anti-HBcAg antiserum because it contains both anti-HBcAg and anti-HBeAg activities. Mesangial deposits of HBsAg were detected in 40% and 21% of renal biopsies from HBsAg carriers with mesangial IgA nephropathy by polyclonal and monoclonal antibodies, respectively. The authors' study confirms that HBeAg is the predominant HBV antigen deposited in HBV-associated membranous nephropathy, and glomerular HBsAg deposits are detected in some HBsAg carrier with mesangial IgA nephropathy. Careful testing and evaluation of each antibody are necessary to prevent misinterpretation.     

Immunopathological correlation between mesangial C3d-deposition and C3d-fixing circulating immune complexes in lupus nephritis

By a direct immunofluorescent technique, glomerular C3d deposition was examined in a total of 50 renal biopsy specimens from patients with lupus nephritis. C3d deposition was then compared with disease activity, glomerular IgG and C3c deposition, and the levels of circulating immune complexes (CIC) measured by a solid-phase anti-C3d assay. There was a good correlation between disease activity and the positivity of glomerular C3d deposits (P less than 0.001), as well as C3c deposits (P less than 0.001). Even in clinically inactive patients, a relatively high percentage (59%) of C3d deposits were positive compared with C3c deposits (17%). Mesangial C3d deposition correlated with clinical disease activity more significantly (P less than 0.005) than capillary wall C3d deposition (P less than 0.025). C3d deposits were detected in all of the 30 cases with positive C3c deposits, and moreover, in 15 of the 20 (75%) cases with negative C3c deposits. Glomerular IgG deposits were almost always associated with C3d deposits, both in mesangial areas and along capillary walls, with statistical significance (P less than 0.005, P less than 0.001, respectively). The serum levels of C3d-fixing immune complexes (IC) were significantly correlated with the positivity and intensity of mesangial C3d deposits. This study demonstrates glomerular deposition of C3d in patients with lupus nephritis and reveals a significant correlation between mesangial C3d deposition and disease activity.     

The thin glomerular basement membrane in children with haematuria

To determine the specificity and significance of widespread attenuation of the glomerular basement membrane on electron microscopy, 240 renal biopsies from 218 children were studied retrospectively. Twenty-three patients showed diffuse attenuation and three of them are cases of hereditary nephritis. The other 20 patients are characterized by persistent microscopic haematuria, absence of proteinuria, normal blood pressure and renal function, and minimal glomerular changes. In 10 of these 20 children, microscopic haematuria was also present in the family. We conclude that widespread attenuation of the glomerular basement membrane is a characteristic of benign familial and non-familial haematuria. The thin glomerular basement membrane may be responsible for the haematuria and may result from incomplete glomerular maturation.     

IgA nephropathy associated with chronic hepatitis B virus infection in adults: the pathogenetic role of HBsAG

Five adult cases of IgA nephropathy associated with chronic hepatitis B virus infection were studied. Serum HBsAg and anti-HBc were present in five patients and HBeAg in four patients. Glomerular changes were typical of primary IgA nephropathy in four patients, and a mixed picture of IgA and membranous nephropathy was demonstrated in one patient. Immunofluorescence microscopy using polyclonal and monoclonal antibodies against HBsAg, HBcAg, and HBeAg revealed mesangial deposits of HBsAg in renal biopsies from four patients. One renal biopsy showed only mesangial and capillary HBcAg by polyclonal antiserum, and virus-like particles were demonstrated in the intramembranous electron-dense deposits on ultrastructural examination. Mesangial HBeAg was not detected in the renal biopsies from these patients with IgA nephropathy. As for the single patient with a mixed picture of IgA and membranous nephropathy, granular deposits of HBeAg with a distribution similar to IgG were detected in the glomerular capillary walls in addition to the mesangial deposition of HBsAg. These findings suggest that HBsAg rather than HBeAg may play a role of the pathogenesis in some of the adult patients with IgA nephropathy associated with chronic hepatitis B virus infection.     

Fibronectin and basement membrane components in renal amyloid deposits in patients with primary and secondary amyloidosis.

Kidney biopsies from one patient with primary (AL) and three with secondary (AA) amyloidosis were used for an ultrastructural study of the collocalization of basement membrane proteins and the extracellular matrix protein fibronectin within amyloid deposits. Antibodies against amyloid P component, laminin, and heparan sulphate proteoglycan core protein all reacted with the basement membranes and the amyloid depositions in AA and AL amyloidosis. Monoclonal and polyclonal antibodies against collagen type IV reacted only with the basement membranes. Anti-fibronectin reaction was found in association with the basement membranes in all four cases, while labelling of amyloid depositions was found only in one of the AA amyloid cases and in the AL amyloid depositions. It is concluded that basement membrane components may be of importance for the formation of amyloid fibrils.     

兔肾小管基底膜所致Wistar大鼠肾小管间质性肾炎模型的建立及环磷酰胺对其防治作用

选用兔肾小管基底膜（ＴＢＭ）、完全福氏佐剂及百白破疫苗免疫雌性Ｗｉｓｔａｒ大鼠，成功地建立了肾小管间质性肾炎（ＴＩＮ）模型。实验证明在ＴＩＮ发生时，ＴＢＭ上有ＩｇＧ和Ｃ３沉积，肾间质大量单个核细胞浸润，主要是淋巴细胞，部分有肉芽肿形成。随后出现肾小管萎缩和肾间质纤维化。用环磷酰胺可以抑制ＴＩＮ的发生和进展，其作用机制可能是抑制细胞免疫反应     

Antigens of the human liver.

Bovine myelin basic protein was found to agglutinate polystyrene particles coated with human polyclonal IgG, monoclonal IgG1, or IgG Fc fragments, but not those coated with IgG F(ab')2 fragments, IgA, or IgM. The agglutination of Fc-coated particles was inhibited by heat-aggregated polyclonal IgG or monoclonal IgG2, IgG3 and IgG4, but not by native IgG. Reduction and alkylation of aggregated IgG did not affect their inhibitory activities. Soluble immune complexes displayed the highest inhibitory activity at a two-fold antigen excess. The interaction between myelin basic protein and aggregated IgG was confirmed by gel exclusion experiments on Sephadex G-200. The possible consequence of these findings could be significant in the interpretation of IgG deposits in brain plaques of multiple sclerosis patients and of the results of immunohistochemical studies, titration of anti-myelin basic protein antibodies and immunoassay of myelin basic protein.     

Morphology of IgA nephritis (Berger disease). Immunohistologic, light- and electron microscopic findings

An IgA nephritis was diagnosed in 109 (24%) out of 445 renal biopsies with glomerular disease in the years from 1977 to 1985. The mean age of the patients in question was 29 years. The male:female sex ratio was 2.6:1. Immunohistologically, the characteristic branching mesangial IgA deposits were uniformly present. In addition 96% showed mesangial C3 and 54% mesangial IgG and/or IgM deposits. Besides, immunoglobulin and/or C3 deposits could be detected at glomerular basement membranes (20%). The histological types of IgA nephritis were minor glomerular abnormalities (10%), focal/segmental glomerulonephritis (29%), diffuse mesangioproliferative (58%), membranoproliferative (1 case), and sclerosing glomerulonephritis (2 cases). Additional tubulointerstitial lesions were found in 55%. Electron microscopically, in 53 cases under study, mesangial electron dense immunodeposits were seen. At the glomerular basement membranes, deposits could be found only in 23 examined cases (43%). The comparison of clinical data with morphological findings showed relationships between the degree of proteinuria and creatinine level increase with the histological type of IgA nephritis and with the degree of glomerular sclerosis, tubulointerstitial lesions, and electron microscopically proved glomerular basement membrane deposits. Hematuria seemed not to correlate with the morphological picture.     

Immunofluorescence characterization of light chains in human nephropathies

Summary Renal tissue from 185 patients with various nephropathies were studied by immunofluorescence, in order to look for the frequency and potential predominance of kappa or lambda light chain glomerular deposits. Four normal renal biopsies were used as controls. An overall study shows that light chains were present in glomeruli in 136 out of 185 cases; kappa light chain deposits were more frequent than lambda light chain deposits (73,5% and 64,3% respectively). An analytical study shows that this was not observed in all nephropathies studied. In mesangial IgA nephropathy, lambda light chain deposits were seen in 81% of cases (29 out of 37) and kappa light chain deposits were observed in 78% (30 out of 37 cases). In lupus nephritis, lambda light chain deposits were present in 13 out of 14 cases (92,8%) whereas kappa light chain deposits were demonstrated in 12 cases (85,7%). In other nephropathies such as membranous, endocapillary proliferative and amyloid nephritis, kappa was the predominant light chain observed in glomeruli or was present in the same number of cases as lambda light chain (mesangiocapillary glomerulonephritis). These findings show that in certain nephritides, for example IgA nephropathy and lupus nephritis, IgA and IgG deposits are mainly composed of lambda light chain in contrast with the normal kappa:lambda ratio in human serum of 2:1.     

Hereditary nephritis mimicking immune complex-mediated glomerulonephritis

The defining ultrastructural features of hereditary nephritis are "basket weave" lamellation or thinning of glomerular basement membranes. Electron-dense deposits are not seen and immunofluorescence (IF) is generally negative. In this study, we report 5 cases of hereditary nephritis in which substantial amounts of glomerular electron-dense deposits were identified on electron microscopy, with corresponding positive IF staining in 4 cases, suggesting immune complex-mediated glomerulonephritis. However, no case had histological evidence of glomerular endocapillary or extracapillary proliferation or leukocyte infiltration typical of active glomerulonephritis. Four cases were diagnosed at outside institutions simply as forms of glomerulonephritis without considering the possibility of hereditary nephritis and were sent for consultation in contemplation of possible immunosuppressive therapy. All patients had negative serologies and no known underlying infectious or autoimmune disease; 4 patients had family history of hematuria or renal disease. The glomerular electron-dense deposits were predominantly mesangial (4 cases) and intramembranous (4 cases), as well as subepithelial (2 cases) or subendothelial (1 case). Corresponding IF positivity for immune reactants was identified in 4 cases, and IgG was the predominant immunoglobulin deposited. A characteristic feature was the tendency for deposits to form between the complex layers of glomerular basement membrane material, favoring a process of nonspecific entrapment of immune reactants within the thickened, lamellated basement membrane. In all cases, a diagnosis of hereditary nephritis was confirmed by demonstration of the characteristic loss of immunoreactivity for the alpha5 subunit of collagen IV (4 cases) or Goodpasture's antigen (1 case) in renal or epidermal basement membranes. These cases expand the spectrum of unusual pathological findings in hereditary nephritis and emphasize the potential for hereditary nephritis to mimic immune complex glomerulonephritis.     

Identification of a 400-kd protein in the brush borders of human kidney tubules that is similar to gp330, the nephritogenic antigen of rat Heymann nephritis.

The nephritogenic antigen of Heymann nephritis (HN)--a well-studied experimental rat model disease of human membranous glomerulonephritis (MGN)--was recently shown to be a 330-kd glycoprotein (gp330) which is present in the membranes of both the rat tubular brush borders and of podocytes. Because the pathogenic antigen(s) of MGN are unknown, the authors have searched for a gp330-like molecule in human kidney and for its role in MGN. The authors here report that a membrane protein (apparent molecular weight 400 kd) is present in human kidney which is immunologically cross-reactive with rat gp330. By immunoelectron microscopy (using rabbit anti-rat gp330 IgG or a monoclonal anti-400-kd IgG) this molecule is similarly localized in human proximal tubules, but it is absent from the podocytes of human glomeruli. The 400-kd molecule is not detected in the glomerular immune deposits of 30 biopsies of MGN. It is proposed that this is due to the lack of the 400-kd protein in human glomeruli which prevents the formation of initial 400-kd anti-400-kd IgG immune complexes in situ.     

Isolation and characterization of the tubular basement membrane antigen associated with human tubulo-interstitial nephritis.

The target antigen, a 54-kD glycoprotein (gp54), reactive with sera from patients with anti-tubular basement membrane (anti-TBM) nephritis, was isolated from collagenase-digested (CD) bovine TBM. The purified gp54 was shown to be non-collagenous by amino acid analysis, and to be a unique basement membrane component by amino-terminal sequencing. The nephritogenicity of gp54 was demonstrated by immunizing strain XIII guineapigs with purified gp54, and producing anti-gp54 antibody and tubulo-interstitial nephritis. Anti-gp54 antibody, affinity-purified from sera of patients with anti-TBM nephritis, bound by immunoblotting to 54-kD and, to a lesser extent, 48-kD components of partially purified human CD-TBM. Indirect immunofluorescence showed that gp54 was present in the basement membrane of proximal tubules of the kidneys of normal human, cow, rabbit, guineapig and Brown-Norway rat but not in Lewis rat. Immunoelectron microscopy revealed localization of gp54 along the interstitial side of the TBM and its association with interstitial collagen fibres. These results indicate that gp54 is the nephritogenic antigen involved in tubulo-interstitial nephritis, and is unique in chemical characteristics and localization in the kidney.     

Localization of 20-kD homologous restriction factor (HRF20) in diseased human glomeruli. An immunofluorescence study.

The 20-kD homologous restriction factor (HRF20), which is identical to CD59, is a membrane-associated protein which inhibits the reaction of C9 to form membrane attack complex (MAC) of homologous complements. In various human glomerular diseases deposition of complement components is frequently seen and MAC is reported to associate with immune deposits. Using a specific monoclonal antibody, 1F5, against HRF20, we attempted to study the localization of HRF20 in human glomerulonephritides and to compare the localization of HRF20 with those of immune deposits and MAC. The frozen sections of kidney specimens were fixed in acetone at room temperature before staining. In normal kidneys and kidney specimens from the patients with minimal change nephrotic syndrome, membranous nephropathy, and IgA nephropathy, HRF20 was strongly localized in the peritubular capillaries and along Bowman's capsules. A weaker but well-defined staining was obtained in the mesangial area and faint staining was seen along the glomerular capillary walls. In contrast, glomerular capillary walls were rather strongly stained in the cases with diffuse lupus nephritis which had subendothelial dense deposits. These data suggest that HRF20 (CD59) is present in the human glomeruli and its expression is enhanced under certain conditions such as lupus nephritis.