Immunohistochemical distinction between amyloidosis and fibrillar glomerulopathy.

Six patients with glomerulonephritis and glomerular proteinaceous deposits constituted by fibrillar ultrastructures similar to those of amyloid but lacking the Congo red tinctorial affinity characterizing amyloid were studied. Clinically, these patients had proteinuria and hematuria; in addition, three patients had hypertension and one renal failure. Protein deposits in their kidney biopsy sections were evaluated by immunofluorescence, immunoperoxidase, and immunoelectron microscopic (protein A-gold) techniques, using antibodies against IgG, IgA, IgM, C3, C1q, fibrinogen, immunoglobulin kappa and lambda light chains, and against amyloid fibril proteins of different types, including AA, A lambda, A kappa, and AF. By immunofluorescence and immunoperoxidase, in all cases the deposits stained intensely with antibodies against IgG, C3, and kappa and lambda light chains; one case also showed C1q immunoreactivity. By contrast, none stained with antibodies against various amyloid fibril proteins. Immunoelectron microscopic findings corroborated this data, indicating that the nonamyloid fibrillar deposits studied are antigenically distinct from known amyloid deposits and that they contain IgG-derived material.     

Nephrotic syndrome in a patient with IgA deficiency-associated mesangioproliferative glomerulonephritis

A case of mesangioproliferative glomerulonephritis in a 55-year-old woman with selective IgA deficiency and serum antinuclear antibodies who presented with nephrotic syndrome is described. The patient did not have clinical or laboratory features of systemic lupus erythematosus (SLE) other than antinuclear antibodies. Histology of the patient's renal biopsy revealed a mesangioproliferative glomerulonephritis and direct immunofluorescence showed that paramesangial deposits contained predominant IgM with lesser IgG, C3 and C1q. These findings are identical to those previously described in a form of glomerulonephritis associated with IgA deficiency and would be atypical for lupus nephritis. Glomerulonephritis is not a well recognized complication of IgA deficiency, though it has been rarely reported in the literature. This case provides further evidence that IgA deficiency is associated with a unique immune complex-mediated glomerulopathy with characteristic immunopathological and ultrastructural features. It is the first reported case to present with nephrotic syndrome.     

Immune complexes in patients with drug eruptions: the relationship between skin lesions and circulating immune complexes.

The relationship between skin lesions and immune complexes was studied in sixty-two patients with exanthematic drug eruptions. By means of C1q-binding, conglutinin-binding and platelet aggregation tests, immune complexes were detected in a considerable number of sera from these patients. Patients with widespread maculopapular drug eruptions were found to show a relatively high serum level of immune complexes. There was a close association between the disease activity and the amount of the circulating immune complexes. By immunofluorescence, six of seventeen patients with drug eruptions were shown to have deposits of IgG, IgM, IgA or C3 in the skin lesions. These results suggest that certain immune complexes may play a role in some types of drug eruption as a pathogenetic factor.     

Membranoproliferative glomerulonephritis. Localization of early components of complement in glomerular deposits.

A body of evidence suggests that in membranoproliferative glomerulonephritis (MPGN), complement is activated by the alternate pathway. Therefore, deposition of early components of complement should not be expected in glomeruli. The renal tissues of 16 patients--13 with classic MPGN and 3 with dense deposit disease, a variant of MPGN--were studied by light and electron microscopy and by means of elution and immunofluorescence for the localization of complement (C1q, C4, and C3), immunoglobulins (1gG, IgM, and 1gA), and other serum proteins. Variable amounts of C3, C4 and/or C1q, and IgM were detected in the glomeruli of all patients, whereas IgG and IgA were present, respectively, in 15 of 16 and 6 of 16 patients. Deposits were localized in mesangium and in peripheral capillary loops in a typical lobular distribution. The specificity of each antiserum was verified by immunodiffusion, immunoelectrophoresis, and blocking experiments utilizing unlabeled antibody. Glomerular-bound IgG was eluted with acid citrate buffer, suggesting that IgG might be complexed with antigen(s) in glomerular deposits. By light microscopy, lesions ranged from focal proliferation and lobulation to more severe involvement with typical splitting of glomerular basement membranes, sclerosis, and less frequently, crescent formation. Ultrastructurally, all patients with classic MPGN exhibited mesangial and subendothelial deposits, and in 5 of these patients, subepithelial deposits were demonstrated. With the exception of ultrastructural lesions, patients with the dense deposit variant lacked distinguishable features when compared with those with classic MPGN. The significance of these findings is discussed in relation to a) activation of complement and the possible role of an immune complex mechanism and b) the variability of the morphologic expression.     

The role of circulating immune complexes in the glomerular disease of experimental hepatosplenic schistosomiasis.

The serological and renal changes were studied simultaneously in 115 mice infected with Schistosoma mansoni. IgG and IgM, but not IgA anti-S. mansoni antibodies were detected in the sera, together with circulating immune complexes containing schistosomal antigen. Glomerular mesangial deposits of IgA, IgM and C3 were observed. Despite the strong correlation observed between the occurrence of the circulating immune complexes containing schistosomal antigen and the glomerular deposits, results concerning the behaviour of IgA suggest that portal hypertension and liver damage have a role in the pathogenesis of glomerular lesions.     

Kidney lesions in baboons infected with Schistosoma mansoni.

Glomerular lesions in baboons (Papio anubis) infected with different dosage regimes of Schistosoma mansoni were studied by immunofluorescence and light microscopy on kidney sections and by countercurrent immunoelectrophoresis on kidney homogenates and tissue eluates. Mild lesions, characterized by focal and segmental deposits of immune complexes, developed in sixty-two out of 103 baboons, irrespective of the intensity and duration of the infection. Severe, diffuse lesions developed in six baboons after prolonged and heavy infections. Adult worm and soluble egg antigens, together with IgM, IgG and C3, were detected in most of the severe lesions and in some of the mild lesions. In some animals, antigens were detected in most of the severe lesions and in some of the mild lesions. In some animals, antigens were detected in acid homogenates and eluates of kidneys which showed no deposits of immunoglobulins or complement. These observations indicate that renal lesions in S. mansoni infections may be attributable to the deposition of immune complexes pre-formed in the circulation. However, the demonstration of antigens alone in some animals may suggest an alternative possibility, namely that antigens are deposited first with a subsequent binding of antibody and complement.     

Immunohistopathologic evaluation of C1q in 800 renal biopsy specimens

The frequency, distribution, and intensity of C1q localization were evaluated in 800 renal biopsy specimens, and these observations were correlated with light, immunofluorescence, and electron microscopy findings. Intense C1q immunostaining was most frequent in proliferative and membranous lupus glomerulonephritis and in a recently described form of proliferative glomerulonephritis designated "C1q nephropathy." Moderate intensity C1q immunostaining was observed in most cases of type I but not type II, membranoproliferative glomerulonephritis. Unlike lupus membranous glomerulopathy, non-lupus membranous glomerulopathy usually did not have extensive C1q localization. C1q was scanty or absent in IgA nephropathy and antiglomerular basement membrane antibody mediated glomerulonephritis. C1q, along with IgM and C3, was often present at sites of glomerular sclerosis, especially in focal segmental glomerulosclerosis. Extraglomerular C1q was most frequent and most intense in cases of lupus nephritis having extraglomerular immune deposits. The presence or absence and intensity of C1q immunostaining were shown to be useful in the differential diagnosis of some glomerulopathies.     

Renal immunopathology in renal cell carcinoma

Summary Signs of glomerulopathy, especially a nephrotic syndrome can occur in cancer patients, but the exact frequency of glomerular lesions is not well known in these patients. To define this frequency in a given type of malignancy we have studied the nephrectomy kidneys in 40 patients with renal cell carcinoma. Proteinuria, which was present in 7 cases, ranged from 0.15 to 1.5 g per 24 h. Reduction of the creatinine clearance greater than 50% was observed in 5 patients. Circulating immune complexes were detected in 11 of the 15 patients studied. Carcinoembryonic antigens were noted in 2 of 9 patients investigated. Research of alpha 1 foetoprotein carried out in 12 patients was always negative. HBs antigen or Hbs antibodies were detected in 6 of 29 patients studied. Light microscopic examination of the normal uninvolved kidney tissue showed obvious glomerular lesions (mesangial hypertrophy with or without deposits, with or without cell proliferation) in 7 patients (17.5%). Amyloid deposits were never observed. Immunofluorescence study revealed mesangial deposits in 35% of patients versus 5.4% of control subjects (P < 0.0001). These deposits included C3 and/or IgM in 13 cases, IgA and C3 in one case. No fixation was observed, neither on tubules of normal tissue nor on carcinoma lesions. This report demonstrates that glomerular deposits are usually found in approximately one third of patients with renal cell carcinoma and that these deposits are located in the mesangial areas and not in the subepithelial space as it is often observed when glomerulonephritis is expressed by clinical symptoms.This work is supported by INSERM n^oCSSV, 78.5.206.5     

IgA-associated renal diseases: Antibodies to environmental antigens in sera and deposition of immunoglobulins and antigens in glomeruli

Levels of IgA1, IgA2, IgM, and IgG antibodies specific for 10 ubiquitous food and bacterial antigens were examined by radioimmunoassay in the sera of 29 patients with IgA-associated renal diseases and 22 normal individuals. No significant differences were observed between patient and normal groups in the levels of IgA1 antibodies, and IgA2 antibodies were detected in only a few individuals in either group. Minor differences in IgM or IgG antibodies were seen against some antigens. Significant positive correlations between IgA1 and IgG and between IgA1 and IgM antibodies to casein were found in the patient group. Analysis of the molecular form of serum IgA1 antibodies revealed that although the pattern of polymeric and monomeric forms varied between individuals and between antibody specificities, there was no preponderance of one form in either patient or normal groups. Examination of kidney biopsies from 50 patients with IgA-associated renal diseases revealed that IgA1 represented the predominant subclass deposited in the glomerular mesangium; glomeruli from three patients contained both IgA1 and IgA2. Seventy-eight percent of the patients also had deposits of IgM, although IgA and IgM deposits did not always coincide. When IgG was present in glomeruli (45% of patients), the IgG1 subclass predominated. J chain was detectable in glomeruli of only four patients. C3 was detected in glomeruli of 95% of the patients, although the distribution of C3 did not always coincide with that of IgA. Indirect immunofluorescence staining with rabbit antisera to various environmental antigens showed that milk protein antigens could be deposited in association with IgA in the glomerular mesangium.     

Treponemal antigen in immunopathogenesis of syphilitic glomerulonephritis.

A patient with syphilitic glomerulonephritis had a renal biopsy and was treated for secondary syphilis. Light, electron, and immunofluorescence microscopic studies revealed an acute proliferative glomerulonephritis with subepithelial, intramembranous, and subendothelial immune complex deposits containing IgG, IgA, IgM, C4, and C3. Similar local deposits containing predominantly IgM were noted in areas of mesangial proliferation. Indirect fluorescent antibody studies employing rabbit treponemal antibody and sheep antirabbit globulin conjugate revealed the presence of treponemal antigen in the glomerular deposits. This finding provides strong evidence for the immunopathogenesis of the glomerular lesion as well as a causal link with Treponema pallidum.     

Electron-dense subepithelial glomerular deposits in Henoch-Sch?nlein purpura syndrome.

A case of Henoch-Sch?nlein purpura (HSP) with renal lesions is presented. The clinical, laboratory, and morphologic findings revealed features commonly described in HSP. A renal biopsy revealed diffuse, generalized, proliferative glomerulonephritis. The unusual findings in this case were numerous electron-dense subepithelial deposits ("humps") and a few small intramembranous deposits in the glomerular capillaries without deposits in the mesangium, mimicking those of acute poststreptococcal glomerulonephritis. The electron-dense deposits were well correlated with deposits of IgG, IgA, C3, C4, C1q, and fibrin-fibrinogen demonstrated by immunofluorescent microscopy.     

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.     

Histiocytic sarcoma with a granuloma-like component occurring in a large colony of Sprague-Dawley rats.

The presence of circulating immune complexes (ICs), and alterations of serum immunoglobulins G, A, and M, properdin factor B, and C3 and C4 levels were correlated with glomerular immune deposits in 50 consecutive renal biopsy patients. Urine from 25 of these patients was also examined for ICs. Agarose gel zone electrophoresis (AGE) was used for IC screening. This method detects greater than or equal to 200 ng of IC per 1.5 microliter sample application (approximately equal to 130 micrograms/ml of serum immune complexes) and gives some indication of antigen or antibody excess in the ICs. Glomerular immune deposits were detected by immunofluorescence and electron microscopy in 72% (36/50) of these patients. Circulating and/or urinary IC were found in 69% (25/36) of patients with positive immunofluorescence and 78% (11/14) of patients with negative immunofluorescence. Five of 11 patients with circulating IC but no renal deposition presented with idiopathic crescentic glomerulonephritis (ICGN). These results indicate that IC that persist in the circulation and/or pass renal glomeruli with minimal deposition may result in tissue injury. Circulating IC in antibody excess were detected in all patients with membranous glomerulonephritis. ICs were also found in 55% of patients with IgA nephropathy. Our observations support the hypothesis of an immune complex pathogenesis for these diseases. Determination of circulating and urinary IC in patients with glomerular disease may help in clinical assessment and provide information concerning the pathogenesis of these diseases in humans.     

Small vessel vasculitis caused by hepatitis B virus immune complexes: Small vessel vasculitis and HBsAg

In a comprehensive study of 80 patients with vasculitis, 4 had concurrent hepatitis B virus (HBV) infection. Polyarteritis nodosa was present in 2 and in the other 2, cutaneous vasculitis, presenting clinically as palpable or Henoch-Schönlein purpura. In one of these patients skin biopsies demonstrated granular deposits of IgM, C3, C4, and the hepatitis B surface antigen (HBsAg) and electron-dense deposits of aggregated 20-nm particles resembling HBsAg in postcapillary venules. Evidence for circulating HBsAg-immune complexes included increased serum C1q binding activity, decreased serum complement, and a cryoprecipitate containing both HBsAg and IgM anti-HBs. Aggregated 20-nm particles resembling intact HBsAg were also seen by negative staining electron microscopy of the serum cryoprecipitate. This patient fulfills all the criteria for a specific immune complex vasculitis caused by his immune response to a chronic HBV infection. These findings emphasize that HBV infection may be associated with small vessel vasculitis as well as polyarteritis nodosa, mixed cryoglobulinemia, and glomerulonephritis. A similar immune response to other viral infections may be expressed as palpable (Henoch-Schönlein) purpura also.     

Deposition of complement C3c, immunoglobulin (Ig)G4 and IgG at the basement membrane of pancreatic ducts and acini in autoimmune pancreatitis

Detlefsen S, Bräsen J H, Zamboni G, Capelli P & Klöppel G
(2010) Histopathology 57, 825–835 Deposition of complement C3c, immunoglobulin (Ig)G4 and IgG at the basement membrane of pancreatic ducts and acini in autoimmune pancreatitis Aims: Autoimmune pancreatitis (AIP) is a type of pancreatitis whose immunopathogenesis is still unknown. It has been reported that renal biopsy specimens from patients diagnosed with both AIP and tubulointerstitial nephritis reveal deposits containing complement C3, immunoglobulin (Ig)G and IgG4 at the tubular basement membranes (BMs). The aim was to investigate the deposition of complement and immunoglobulins in pancreatic tissue from AIP patients compared to non‐AIP patients. Methods: Double immunofluorescence microscopy for C3c, IgG4 and IgG together with CK7, trypsin, collagen IV, CD31 and CD79a, as well as immunofluorescence microscopy for C1q, IgA and IgM, were performed on frozen pancreatic tissue from AIP and alcoholic chronic pancreatitis (ACP) patients. Results: In AIP patients, complement C3c, IgG4 and IgG were deposited at the collagen IV‐positive BMs of pancreatic and bile ducts and of acini. In a minority of the ACP patients, weak C3c‐positive BM deposits were detected, but no IgG4‐ or IgG‐positive BM deposits were present. Conclusion: The deposition of C3c, IgG4 and IgG at the BM of small‐ and medium‐sized ducts and acini of the pancreas is characteristic of AIP. This suggests that immune complex‐mediated destruction of ducts and acini play a role in the pathogenesis of AIP.     

Immune deposit nephritis in infectious mononucleosis.

A 22-year-old white male (L.V.) died of gram-negative septicemia complicating infectious mononucleosis (IM) that was associated with jaundice and oliguric renal failure. The kidney showed mesangial granular deposits of IgM and C3, mesangial electrondense deposits, and interstitial infiltrates of infiltrates of mononuclear cells, including atypical lymphocytes. Eluates obtained from kidney, spleen and liver contained Paul--Bunnell (PB) antibodies. Presence of PB antigens in these tissues was indicated by absorption of PB antibodies from IM sera, with the sediments resulting from tissue elutions. The IgM mesangial deposits were partially eluted with acid buffer at 56 degrees C and then reconstituted by incubation with IM sera or with immunoglobulins eluted from tissues of patient L.V. The presence in renal structures of PB antigens, IgM heterophile antibody, C3 and electron-dense deposits is consistent with the hypothesis that heterophile immune complexes were localized in the kidney and that they contribute in the pathogenisis of IM nephritis.     

Glomerular alterations associated with obstructive jaundice

An immunohistochemical and clinicopathologic analysis of glomerular alterations was carried out in 20 autopsy cases with obstructive jaundice. The 20 cases without clinical nephritis had primary carcinoma of various locations, including the stomach, rectum, pancreas, and biliary tract. Mesangial IgA deposition was present on immunofluorescence staining in four cases, IgG in two cases, IgM in five cases, and C3 in four cases. Glomerular polymeric IgA containing A1, A2, and J chain was considered to originate from the gastrointestinal tract. All immunofluorescence-positive cases except one had electron-dense deposits in mesangial regions. These findings suggest that glomerular IgA deposition develops in a handful of patients suffering from obstructive jaundice, presumably due to the passive trapping of circulating immune complexes. Furthermore, glomerular IgA deposition in patients with obstructive jaundice is not influenced by duration or intensity of jaundice, and it unlikely induces clinical nephritis.     

Therapy of IgA Nephropathy

IgA nephropathy is the commonest form of glomerulonephritis worldwide, and is one of the major causes of terminal renal failure in most industrialised countries. It is defined by the dominance of IgA mesangial deposits in immunofluorescence studies. Corticosteroid-sensitive nephrosis lipoides (minimal change disease) with IgA deposits and superimposed crescentic glomerulonephritis are to be differentiated from primary IgA nephropathy (Berger's disease). In the latter, clinical manifestations are dominated by synpharyngitic macroscopic haematuria and permanent proteinuria. Terminal renal failure occurs in about 25% of patients after 10 years or more. Heavy proteinuria, hypertension, altered renal function and severe histological lesions at diagnosis are markers of poor prognosis. Primary IgA nephropathy is thought to be related to mesangial deposition of polymeric IgA1-containing immune complexes, owing to altered B cell responses to exogenous and endogenous antigens, together with hyperactivity of T helper type 1 and type 2 cells, both favoured by a genetic background. The 2 compartments of the IgA system (medullary and mucosal) may participate in the pathogenesis of the disease. Modulation of gut-associated lymphoid tissue and immune tonsillectomy are current lines of research. Although impressive results were obtained with an oligoantigenic diet, it is somewhat impractical. Pharmacological modulation of the mucosal immune response seems more promising. There is no proof that phenytoin, a drug which reduces bone marrow IgA synthesis, is beneficial. Emerging data suggest the potential of immune intervention in severely proteinuric patients before sclerotic lesions have occurred, using azathioprine and intravenous immunoglobulins. The benefit of early corticosteroid therapy is still unknown in both adults and children, and the efficiency of alkylating agents is unproven. The search for bacterial foci in primary IgA nephropathy is mandatory, as appropriate treatment may have a protective effect on renal function and help to improve or stabilise some patients. Slowing the progression of renal failure by a combination of ACE inhibitors, fish oil and, possibly, antiplatelet drugs is a promising therapeutic approach.     

IgG4-related kidney disease

IgG4-related disease (IgG4-RD) is a recently recognized systemic immune-mediated disease that can affect nearly any organ or tissue. The most common manifestation in the kidney is IgG4-related tubulointerstitial nephritis (IgG4-TIN), which can present as renal insufficiency, renal mass lesions, or both. Histologically, IgG4-TIN is a plasma cell-rich interstitial inflammatory infiltrate with mononuclear cells, eosinophils, and increased IgG4+ plasma cells, along with expansile interstitial fibrosis that often has a “storiform” appearance. Tubular basement membrane immune complex deposits, best visualized on immunofluorescence staining, are present in most cases. IgG4-TIN usually shows a rapid response to steroid therapy. Glomeruli may be affected by IgG4-RD, usually in the form of membranous glomerulonephritis; other glomerular lesions have also been described. This review describes the different histopathologic patterns of renal involvement by IgG4-RD, with associated clinical, radiographic, and serologic features.     

Immunohistochemical detection of the terminal C5b-9 complement complex in children with glomerular diseases.

Kidney biopsies were obtained in 28 children with glomerular diseases and studied using indirect immunofluorescence and immunoperoxidase for IgG, IgA, IgM, C1q, C3c, C4, fibrinogen and the neoantigens of the terminal C5b-9 complement complex. C5b-9 deposits were detected in glomeruli of 14, in tubules of eight and in vessels of 12 cases. Patients with C5b-9 deposits fared worse than those without such deposits, even with the same histopathological type of glomerulonephritis. The C5b-9 complex suggests an in situ complement activation.