Kazuro Kanatsu

Intraglomerular deposition of intact cross-linked fibrin in IgA nephropathy and Henoch-Schönlein purpura nephritis.

To investigate the significance of intraglomerular coagulation and fibrinolysis in IgA nephropathy (IgA-N) and Henoch-Schönlein purpura nephritis (HSPN), the distribution of intact cross-linked fibrin (XFb) modulated by plasmin activity was examined in 25 patients with IgA-N and in 12 with HSPN. In addition to the conventional method detecting fibrin-related antigen (FRA) with an antibody against fibrinogen, the enhanced intensity of immunoreactivity of cross-linked FRA (KL-FRA) using the monoclonal antibody DD3B6/22 after plasmin exposure was evaluated to assess intraglomerular deposition of intact XFb. Also, intraglomerular invasion of macrophages was detected using the monoclonal antibody KP1 against CD68. Sixteen of a total of 37 specimens (43%) showed increased intensity of XL-FRA staining after plasmin treatment which is considered to reflect the distribution of intact XFb. Increases in the intensity of XL-FRA staining were observed mainly in mesangium and partially along glomerular capillary loops and also in a few cases in the crescents. The incidence (67%) of increases in XL-FRA staining after plasmin exposure in HSPN specimens was significantly higher than that in IgA-N specimens (32%; p < 0.05). In the group positive for XL-FRA after plasmin exposure, the numbers of macrophages per glomerulus were significantly higher (n = 15; mean +/- SD = 1.6 +/- 0.9) than in the negative group (n = 6; 0.5 +/- 0.6; p < 0.01). In HSPN, the number of macrophages per glomerulus (n = 8; 1.9 +/- 1.0) was higher than that in IgA-N (n = 13; 0.9 +/- 0.9; p < 0.05). Based on these results, we conclude that XFb is often produced and distributed in intact form in the glomeruli both in IgA-N and HSPN, associated with a relatively low intraglomerular plasmin activity, and that intraglomerular coagulation may progress in accordance with macrophage infiltration, especially in HSPN.

Demonstration of C3d deposits in membranous nephropathy.

An immunoperoxidase technique for light microscopy was carried out in 16 patients with idiopathic membranous nephropathy in order to determine the role of the complement system in glomeruli. Although C3 deposits are found in 50% of the cases, C3d deposits are identified in all cases in association with IgG deposits. This suggests that C3 deposits are degraded and dissociated from immune complexes. Patients with glomerular C3 deposits showed more proteinuria than those without glomerular C3 deposits. The presence of C3 deposits indicates the importance of proteinuria in human membranous nephropathy.

Immunoelectron Microscopic Studies of IgA Nephropathy

Immunoelectron microscopy was used in this study of IgA nephropathy to examine the relationship between immune deposits and electron-dense deposits seen by electron microscopy, and these findings were correlated with the severity of mesangial proliferation. Immunoelectron microscopic studies for antihuman gamma-chain, alpha-chain, mu-chain, C3, and C3d were performed by the method of Nakane in 16 patients with IgA nephropathy. The patients with minimal glomerular involvement and focal proliferative glomerulonephritis showed electron-dense reaction products of IgA in the paramesangial area, while the patients with diffuse proliferative glomerulonephritis showed electron-dense reaction products of IgA throughout the enlarged mesangial matrix. Immunoelectron microscopy showed electron-dense reaction products of IgA at the same locations as the electron-dense deposits seen on electron microscopy. C3 deposits were identified in 15 out of the 16 patients, but were less dense than IgA deposits. Electron-dense reaction products of C3 contained both positive and negative sites in 7 patients. Extensive C3d deposits were found in all cases in association with IgA deposits. The locations of these deposits were the same as those of the IgA deposits. These findings suggest that C3 deposits dissociate from the immune deposits and that the locations of the immune deposits correlate well with the severity of mesangial proliferation.

An Overlapping Syndrome of IgA Nephropathy and Membranous Nephropathy

This is the first report of primary glomerular disease with both mesangial IgA and subepithelial IgG deposits in the glomeruli at the same time. This nephropathy, discovered in 3 patients, is either a new disease entity or an overlapping of IgA nephropathy and membranous nephropathy. Follow-up studies may clarify the pathogenesis of IgA nephropathy and/or membranous nephropathy. In 1 patient the clinical findings resembled those of IgA nephropathy, and in the other 2 they were those of membranous nephropathy. Light microscopy showed generalized diffuse increases in mesangial cells and matrix, and there was slight capillary wall thickening. In the glomeruli, immunofluorescence microscopy demonstrated both granular deposits of IgA in the mesangium and granular deposits of IgG along the capillary loops. On electron microscopy, electron-dense deposits were identified not only in the mesangium but also on the epithelial side of the glomerular basement membrane. These findings were confirmed by the immunoperoxidase technique in electron-microscopic studies of these antibody classes. These glomeruli contained both the dense reaction products of IgA deposits in the paramesangium and mesangial matrix and the dense reaction products of IgG deposits on the epithelial side of the basement membrane.

Analysis of IgG Immune Complexes in Sera from Patients with Membranous Nephropathy: Role of IgG4 Subclass and Low-Avidity Antibodies

The levels of circulating immune complexes (CIC) were determined using an anti-C3d binding assay in patients with various types of glomerulonephritis (GN). It was found that IgG class CIC were positive in 20% (7/35) of patients with idiopathic membranous nephropathy (MN) and in 80% (8/10) of patients with lupus glomerulonephritis (LN). Of these patients, IgG4 subclass CIC were observed more frequently in 29% of MN and 60% (3/5) of minimum change nephrotic syndrome, and, with less amounts, in 10% (1/10) of membranoproliferative GN (MPGN) and 20% (2/10) of IgA nephropathy. On the other hand, the patients with LN showed a lower positivity (30%) of IgG4-CIC as compared with that of IgG-CIC. In the comparison of mean levels, only MN patients showed significantly higher value than normal individuals (p less than 0.05). In patients with MN, the CIC of the other IgG subclasses (IgG1, IgG2, IgG3) were not significantly elevated and their positivities were low (9-11%). The study on the salt-dependent dissociability of CIC, which is considered to reflect the avidity of antibodies in CIC, showed that the IgG-CIC of 11 of 15 patients with MN were dissociable to various extents even at the physiological concentration. These findings suggested that IgG4 subclass specificity and low avidity may be pathogenic characteristics of IgG-CIC in certain populations of patients with MN.

Relationship of Intraglomerular Coagulation and Platelet Aggregation to Glomerular Sclerosis

In order to investigate the relationship between intraglomerular coagulation and glomerular sclerosis, the distribution of fibrin-related antigen (FRA) in glomeruli without extracapillary lesions was examined by immunoperoxidase microscopy in 80 patients with IgA nephropathy (IgA-N). A total of 302 glomeruli were examined, including 20 with global sclerosis, 31 with segmental sclerosis (SS glomeruli), and 251 nonsclerosed glomeruli. In the nonsclerotic areas of SS glomeruli, the deposition of FRA was significantly greater than in the nonsclerosed glomeruli. In the nonsclerosed glomeruli FRA was mainly found in the mesangium, while in the nonsclerotic areas of SS glomeruli FRA was not only present in the mesangium but also in the endothelium of the glomerular capillary loops. FRA-positive microclots were also often observed attached to the endothelium of the capillaries of the nonsclerotic areas of SS glomeruli. Cross-linked FRA was also observed in the endothelium of the same capillaries using the monoclonal antibody DD3B6/22. Deposition of von Willebrand factor (vWF) was greater in the endothelium than in the mesangium in the same areas. Aggregated platelets adhering to the glomerular capillary walls in these areas were frequently detected using the monoclonal antibody P2. Such distribution of platelets and vWF showed that the endothelium of the nonsclerotic areas of SS glomeruli was more severely damaged than that of nonsclerosed glomeruli. These findings suggest that endothelial cell damage might activate the intraglomerular coagulation, which might be one of the factors in the development of global glomerular sclerosis.

Clinicopathological Study of Patients with Mesangial Isolated C3d Deposition in Various Glomerular Diseases

The clinicopathological findings of isolated mesangial C3d deposition in the absence of other complement components or immunoglobulins are summarized. 55 out of 242 individual human renal biopsies examined by immunoperoxidase microscopy had isolated C3d deposition. This group consisted of 12 patients with chronic glomerulonephritis, 8 with minimal-change nephrotic syndrome, 32 with benign recurrent hematuria, 2 with Bartters syndrome and 1 with Raynauds syndrome. None of these patients had a disorder of the renal function and in all the patients the disease took a benign clinical course. Light-microscopic findings indicated injuries ranging from minor glomerular abnormality to mild diffuse mesangial proliferative glomerulonephritis, and there were no other remarkable findings such as cellular crescents, global sclerosis or interstitial infiltration. By immunoperoxidase microscopy, fine granular deposits of C3d were identified only in the mesangium, and arteriolar C3 staining was seen in 31 of the 55 patients. In 38 of the 42 patients examined by electron microscopy, electron-dense deposits were identified in the mesangial matrix. These findings suggest that isolated C3d deposition is a new entity with benign features both clinically and pathologically.

Circulating Immune Complexes of IgG, IgA, and IgM Classes in Various Glomerular Diseases

In order to examine the correlation between immunoglobulin (Ig) classes of immunoglobulins in circulating immune complexes (CIC) and immunoglobulins in glomerular deposits, we have measured CIC of IgG, IgA and IgM classes in various glomerular diseases. Serum CIC were measured using a modified conglutinin binding assay (K assay) using 125I-labeled anti-gamma, anti-alpha and anti-mu antisera. IgA class CIC were detected in more patients with IgA nephropathy than patients with non-IgA nephropathy. There was an association between the presence of IgG deposits in kidneys and the presence of IgG in CIC. Patients with IgA deposits in their kidneys also had IgA class CIC. There was also an association between the presence of IgM deposits in kidneys and the presence of IgM in CIC. These results suggest that the Ig class in CIC and the Ig class in glomerular deposits were correlated, and that in IgA nephropathy the mesangial IgA deposits may be derived from IgA class CIC.

Infected abdominal aortic aneurysm due to salmonella: CT evaluation

Two cases of infected abdominal aortic aneurysm (IAAA) caused by salmonella are reported and the computed tomography (CT) features are discussed and compared with the pathologic findings. Additionally, a review of the literature was performed. A well-enhanced para-aortic mass (PAM) beyond the calcified intima of the abdominal aorta on the CT, which was initially considered to represent a leakage from the infected aneurysm, was observed in 5 of the 6 reported cases (including ours) and identified as a pseudoaneurysm. In one case, multiple gas collections within the PAM were demonstrated for the first time in IAAA due to salmonella.

Immunoelectron Microscopic Localization of Fibrin-Related Antigen in Human Glomerular Diseases

The distribution of fibrin-related antigen (FRA) in glomeruli was examined by immunoelectron microscopy in 9 patients with idiopathic membranous nephropathy (MN), 8 patients with minimal-change nephrotic syndrome, and 10 patients with IgA nephropathy (IgA-N), using antisera against human gamma--chain, alpha-chain, mu-chain, and fibrinogen. Electron-dense reaction products of FRA were observed in the endothelium, subendothelium, and/or in electron-dense deposits (EDD). Among the three glomerular diseases, the amount of electron-dense reaction products of FRA in the endothelium was highest in MN. This suggests that coagulation occurs on the endothelium in MN. Although the mesangial EDD of IgA-N were intensely stained with reaction products of FRA, the staining was weak in the subepithelial EDD of MN. This suggests that FRA hardly penetrates into the subepithelial EDD in MN.