Renal cell carcinomas and pancreatic adenocarcinomas produce nidogen in vitro and in vivo.

The production of nidogen by four renal cell carcinoma (RCC) and three pancreatic adenocarcinoma (PAc) cell lines has been studied in cell culture and in xenografted tumours in nude mice. In RCC cells, immunoreactivity for nidogen was seen only after exposure to monensin to induce cytoplasmic accumulation of secretory proteins. In PAc cells, immunoreaction was also detectable in control cells. Immunoblotting of control and monensin-exposed cells and immunoprecipitation of culture media of radioactively labelled cells demonstrated the production of nidogen polypeptide of Mr ca. 150000 by six of the seven cell lines. Basement membranes (BMs) and stroma of the xenografted tumours derived from these six cell lines demonstrated immunoreactivity for both human and mouse nidogen, as revealed with species-specific antibodies. The ability of the cells to produce nidogen in vitro and deposit in vivo was positively correlated with high histological grade of the xenografted tumours, although the small number of cell lines studied calls for further studies to confirm this. The distribution of nidogen in human RCC and PAc specimens was also studied by immunohistochemistry. There was strong immunoreactivity for nidogen in tumour stroma, BM of carcinoma cell nests, and endothelial basal lamina, but no conclusions could be drawn regarding histological grade and immunostaining patterns, because stromal production could not be ruled out. The results show that nidogen is produced by human carcinoma cells both in vitro and in vivo.

Childhood membranous nephropathy, circulating antibodies to the 58-kD TIN antigen, and anti-tubular basement membrane nephritis: an 11-year follow-up.

Childhood membranous nephropathy (MNP) with anti-tubular basement membrane (anti-TBM) nephritis is a rare disorder that may have extrarenal manifestations. This article describes a new case to be added to the 10 previously reported. A renal biopsy specimen from a 1-year-old white boy with nephrotic syndrome, microhematuria, and hypertension showed MNP (granular global IgG, IgA and C3, and segmental IgM and C1q) associated with hypercellularity and granular deposits of IgM and C1q in the mesangium, arteriolar IgA, and linear TBM IgG, IgA, and C3. A biopsy at age 4 years showed MNP (IgG and C3) and linear IgG and C3 along the TBM. Six months later, temporary glucosuria suggested a mild tubular dysfunction. Biopsy at age 8 years showed sclerosing MNP (IgG and C3), linear TBM IgG and C3, and chronic active tubulointerstitial nephritis (TIN). Indirect immunofluorescence showed circulating anti-TBM antibodies, and the enzyme-linked immunosorbent assay (ELISA) approach verified strong reactivity with the 58-kd TIN antigen. Despite trials with steroids, chlorambucil, azathioprine, and cyclosporine, end-stage renal disease developed by the age of 9 years. At age 10 years, the patient received a cadaveric kidney transplant. With the patient now aged 12 years, the graft is still functioning well, without any clinical evidence of disease recurrence. Neurological, ocular, and abdominal symptoms, including nonbacterial diarrhea, were observed during the follow-up period. The pathophysiology of these extrarenal symptoms remains unclear. Serotyping and genotyping of HLA antigens (A2, A10, B12, B41, DR5 [1101, 1103-4, 1106 or 1108-1113], DR6 [1303, 1312, or 1413], DRB3 [*0101 and 0201-2 or 0301], DQA1 [*0501 homozygous], and DQB1 [*0301 homozygous]) did not indicate any HLA association similar to those described previously in childhood MNP with anti-TBM nephritis (HLA-B7 in four patients, HLA-DR8 in two patients). The presented case is the fifth in the literature that displays reactivity with the 58-kd TIN antigen, and for which data on HLA antigens are reported.

Tubulointerstitial nephritis antigen (TIN-ag) is expressed in distinct segments of the developing human nephron.

Tubulointerstitial nephritis antigen (TIN-ag) is a 58 kDa glycoprotein restricted within the kidney to basement membranes underlying the epithelium of Bowman's capsule and proximal and distal tubules. Autoantibody formation against this component has been described in association with primary immune-mediated tubulointerstital nephritis, membranous nephropathy and anti-glomerular basement membrane nephritis. In the present report, the ontogeny of this protein was studied in human fetal kidney tissue by immunohistochemical analysis of immature and developing nephrons using a panel of monoclonal and polyclonal antibodies. TIN-ag is first detected in basement membranes underlying the epithelium of Bowman's capsule of early capillary loop stage glomeruli and the primitive proximal tubule. No detectable expression is observed in the basement membranes of the branching ureteric bud, nephrogenic vesicle, or comma shape and s-shape stages of nephrogenic development. Increased staining of the proximal tubular basement membrane is associated with outgrowth of the primitive tubule from the urinary pole of the developing glomerulus. In more mature fetal tubules, TIN-ag expression closely resembles that of previously reported observations in mature tissue where it is present in high amounts in the basement membranes of proximal tubules, and to a lesser extent in Bowman's capsule and distal tubules. Our results suggest that TIN-ag expression is developmentally regulated in a precise spatial and temporal pattern throughout nephrogenesis.

Alterations of corneal extracellular matrix after multiple refractive procedures: a clinical and immunohistochemical study.

PURPOSE: To describe the clinical course and alterations of the corneal extracellular matrix (ECM) and basement membrane (BM) in a cornea after hexagonal keratotomy, transverse keratotomies, and keratomileusis. METHODS: Frozen sections of this cornea and of 12 normal corneas were studied by immunofluorescence with specific antibodies. The patient history was analyzed to allow a clinical correlation. RESULTS: In the treated cornea, keratotomy scars and subepithelial fibrosis with neovascularization were seen. Around and beneath the epithelial plugs and along the keratotomy scars, deposits of types III, VI, VIII, and XIV collagen; fibrillin-1; fibronectin; and tenascin-C were found, together with short streaks of types IV (alpha 1-alpha 2) and VII collagen, laminin-1 and -5, entactin, and perlecan. alpha 3-alpha 4 Type IV collagen chains were abnormally absent from the BM around the epithelial plugs. At the edges of the keratomileusis flap, subepithelial fibrosis areas were found, with abnormal deposits of eight different collagen types, perlecan, fibronectin, fibrillin-1, and tenascin-C. The major part of the flap interface did not show ECM abnormalities. ECM alterations outside the scarred areas included the appearance of tenascin-C in the stroma and of alpha 1-alpha 2 type IV collagen in the epithelial BM, and the disappearance of fibronectin from Descemet's membrane. CONCLUSION: Five years after surgery, the treated cornea still presented BM abnormalities at sites of keratotomy scars and epithelial plugs. Several ECM components were abnormally expressed outside the scarred areas, consistent with an ongoing fibrosis in the treated cornea.

Abnormalities of the extracellular matrix in keratoconus corneas.

PURPOSE: To study alterations of the extracellular matrix (ECM) and basement membrane (BM) components in human keratoconus corneas. METHODS: Fifteen normal and 13 keratoconus corneas were characterized by immunofluorescence with antibodies to 23 ECM and BM components. RESULTS: Keratoconus staining patterns for posterior nonscarred regions and Descemet's membrane were normal. We focused on three areas of keratoconus corneas: (a) nonscarred anterior corneal regions, (b) scarred anterior and posterior corneal regions, and (c) gaps in Bowman's layer. In each of these areas, consistent ECM and BM changes could be found. Nonscarred regions showed decreased staining of the epithelial BM for entactin/nidogen, fibronectin, alpha 3-alpha 5 chains of type IV collagen, and chains of laminin-1. In contrast, scarred regions had greater than normal staining of the epithelial BM for these same components and also for laminin-5, perlecan, and type VII collagen. In the Bowman's layer gaps/breaks, focal fibrotic deposits containing type VIII collagen, fibrillin-1, tenascin-C, alpha 1-alpha 2 type IV collagen, and normal stromal ECM and epithelial BM components were seen. Fibrotic regions were largely restricted to areas where, because of the lack of Bowman's layer, the epithelium was in contact with the stroma. CONCLUSIONS: In a single keratoconus cornea, abnormalities in the ECM/BM patterns were not uniform. This may reflect locally increased protease activity (where few if any BM components are found) and ongoing wound healing (where more BM or ECM components or both are found).

Detection of tubulointerstitial nephritis antigen (TIN-ag) in Lewis rat.

Tubulointerstitial nephritis antigen (TIN-ag) is a recently described basement membrane component reactive with autoantibodies in some forms of autoimmune mediated tubulointerstitial nephritis. Immunofluorescence studies using polyclonal and monoclonal antibodies have indicated a restrictive tissue distribution for TIN-ag, with the site of most prominent expression the kidney tubular basement membrane. However, Lewis rat does not demonstrate any immunoreactivity for TIN-ag and does not develop tubuloinsterstitial nephritis after injection of tubular basement membrane material. As TIN-ag would appear to be a molecule of biological significance, experiments were designed to explore the presence or absence of this macromolecule in the Lewis rat model. Southern blotting of Lewis rat genomic DNA revealed the presence of gene sequences corresponding to TIN-ag. RTPCR analysis of Lewis rat kidney cortex total RNA illustrated the expression of a TIN-ag gene product. Western blotting demonstrated the presence of TIN-ag protein forms in kidney cortical homogenates of Lewis rat. The data suggest either extensive epitope masking or expression polymorphism of TIN-ag in the Lewis rat.

Basement membrane abnormalities in human eyes with diabetic retinopathy.

Vascular and parenchymal basement membranes (BMs) are thickened in diabetes, but alterations in individual BM components in diabetic eyes, especially in diabetic retinopathy (DR), are obscure. To identify abnormalities in the distribution of specific constituents, we analyzed cryostat sections of human eyes obtained at autopsy (seven normal, five diabetic without DR, and 13 diabetic with DR) by immunofluorescence with antibodies to 30 BM and extracellular matrix components. In non-DR eyes, no qualitative changes of ocular BM components were seen. In some DR corneas, epithelial BM was stained discontinuously for laminin-1, entactin/nidogen, and alpha3-alpha4 Type IV collagen, in contrast to non-DR corneas. Major BM alterations were found in DR retinas compared to normals and non-DR diabetics. The inner limiting membrane (retinal BM) of DR eyes had accumulations of fibronectin (including cellular) and Types I, III, IV (alpha1-alpha2), and V collagen. The BM zone of new retinal blood vessels in neovascularized areas accumulated tenascin and Type XII collagen, whereas normal, diabetic, and adjacent DR retinas showed only weak and irregular staining. In preretinal membranes, perlecan, bamacan, and Types VI, VIII, XII, and XIV collagen were newly identified. Diabetic BM thickening appears to involve qualitative alterations of specific BM markers at an advanced disease stage, with the appearance of DR.

Extracellular matrix alterations in human corneas with bullous keratopathy.

PURPOSE: To uncover abnormalities of extracellular matrix (ECM) distribution in human corneas with pseudophakic and aphakic bullous keratopathy (PBK/ABK). METHODS: Indirect immunofluorescence with antibodies to 27 ECM components was used on frozen sections of 14 normal and 20 PBK/ABK corneas. RESULTS: Fibrillar deposits of an antiadhesive glycoprotein tenascin in the anterior and posterior stroma, epithelial basement membrane (BM), bullae and subepithelial fibrosis (SEF) areas, and posterior collagenous layer (PCL) were revealed in disease corneas. Tenascin in midstroma, which was observed in some cases, correlated with decreased visual acuity. In normal central corneas, tenascin was never found. Other major ECM abnormalities in PBK/ABK corneas compared to normals included: discontinuous epithelial BM straining for laminin-1 (alpha 1 beta 1 gamma 1), entactin/nidogen and fibronectin; accumulation of fibronectin and alpha 1-alpha 2 type IV collagen on the endothelial face of the Descemet's membrane; and abnormal deposition of stromal ECM (tenascin, fibronectin, decorin, types I, III, V, VI, VIII, XII, XIV collagen) and BM components (type IV, collagen, perlecan, bamacan, laminin-1, entactin-nidogen, fibronectin) in SEF areas and in PCL. CONCLUSIONS: The study provides a molecular description of an ongoing fibrosis on the epithelial, stomal, and endothelial levels in PBK/ABK corneas. These fibrotic changes may follow initial endothelial damage after cataract surgery, may be caused by the upregulation of fibrogenic cytokines, and may play a significant role in the progression of bullous keratopathy.

Identification of a cDNA encoding tubulointerstitial nephritis antigen.

Tubulointerstitial nephritis antigen (TIN-ag) is a 58-kDa basement membrane glycoprotein that is recognized by human autoantibodies in certain forms of tubulointerstitial nephritis. To further characterize this macromolecule and isolate cDNAs encoding TIN-ag, amino acid sequences from tryptic peptides were used to design and synthesize primers in order to amplify a probe for screening a rabbit kidney cortex cDNA library. A cDNA encoding TIN-ag was cloned and sequenced. The predicted amino acid sequence deduced from this cDNA includes the chemically determined sequences of peptides derived from TIN-ag, supporting its authenticity. The predicted amino acid sequence also shows that the carboxyl-terminal region of the molecule exhibits a 30% homology with human preprocathepsin B, a member of the cysteine proteinase family of proteins. A domain in the amino-terminal region of TIN-ag contains an epidermal growth factor-like motif that shares homology with laminin A and S chains, alpha 1 chain of type I collagen, von Willebrand's factor, and mucin, suggesting structural and perhaps functional similarities among these molecules. Immunoprecipitation of in vitro generated recombinant protein using a TIN-ag-specific monoclonal antibody (A8), confirms the identity of the isolated TIN-ag cDNA. In this report the cDNA and predicted amino acid sequences of TIN-ag are presented. Knowledge of the primary structure of TIN-ag will facilitate our understanding of the molecular structure of this novel basement membrane component and may provide clues toward understanding its functional role.

Human corneal basement membrane heterogeneity: topographical differences in the expression of type IV collagen and laminin isoforms.

BACKGROUND: The corneal epithelium converges at the peripheral zone (limbus) with the conjunctival epithelium, forming a continuous sheet with phenotypically distinct regions--central, limbal, and conjunctival. The epithelial basement membrane (EBM) is important for corneal functions and cell adhesion, but its regional composition is poorly understood. Current literature is controversial as to the occurrence of type IV collagen in the cornea. The aim of this study was to investigate in detail corneal basement membrane (BM) composition and correlate it with the differentiation state of contributing cells. EXPERIMENTAL DESIGN: Adult human corneas (N = 8) were cryosectioned and analyzed by immunofluorescence with antibodies to 15 BM components and to keratin 3, a marker of corneal epithelial differentiation. RESULTS: A novel type of spatial heterogeneity ("horizontal") in the EBM composition was found between the central cornea, limbus, and conjunctiva. Central EBM had type IV collagen alpha 3-alpha 5 chains, whereas limbal and conjunctival EBM contained alpha 1-alpha 2 chains and also laminin alpha 2 and beta 2 chains. Limbal EBM in addition had alpha 5(IV) chain. Laminin-1 (alpha 1 beta 1 gamma 1), laminin-5 (alpha 3 beta 3 gamma 2), perlecan, fibronectin, entactin/nidogen, and type VII collagen were seen in the entire EBM. Another novel type of BM heterogeneity ("vertical") was typical for the corneal Descemet's membrane: its stromal face had alpha 1(IV) and alpha 2(IV) chains and fibronectin, whereas alpha 3(IV)-alpha 5(IV) chains, entactin/nidogen, laminin-1, and perlecan were present on the endothelial face. CONCLUSIONS: Type IV collagen controversy is the result of the shifts of isoforms in the limbus and conjunctiva. These shifts and the appearance of additional laminins in the limbus may be related to the differentiation state of corneal cells contributing to the EBM formation. Novel types of BM heterogeneity in the human cornea are described: regional (horizontal) in the EBM and vertical in the Descemet's membrane. The first one may be a common feature of converging complex epithelia, whereas the second one may be another unique property of the Descemet's membrane.

Heterogeneity of renal carcinoma.

Monoclonal antibodies were used to study the expression of three recently characterized basement membrane components and two carbohydrate antigens in 11 renal-cell carcinomas, using immunohistological and biochemical techniques. The expression of several site-specific kidney antigens in renal-cell carcinoma were studied to determine the origin of the carcinoma and if it is possible further classify this type of carcinoma. Tubulointerstitial nephritis antigen (TIN) and two alpha-chains of type IV collagen, alpha 1 (IV) and alpha 3 (IV) were studied. In addition the expression of carbohydrate antigens Lex and SLex, which also exhibit site-specific distribution were characterized. Lex and SLex antibodies stained the majority of the tumours. TIN was expressed in 9 of 11 tumours, the alpha 1 (IV) chain was present in all 11, and the alpha 3 (IV) chain in two of the 11 tumours. Interestingly, the two alpha 3 (IV)-positive tumours were the same two that were negative for TIN. In normal tissue alpha 3 (IV) is found in distal tubules while TIN is found in proximal tubules. Our results are consistent with earlier observations that the proximal tubule is the origin of most renal-cell carcinomas, but the results also indicate that renal-cell carcinoma may originate from the distal tubule.

Tubular basement membrane changes during induction and regression of drug-induced polycystic kidney disease.

Defective cell-extracellular matrix (ECM) biophysiology is considered a factor in the development of polycystic kidney disease (PKD). Altered biosynthesis of various ECM components may result in tubular dysmorphogenesis and uncontrolled tubular cystic expansion. In this study, expression of certain ECM components was investigated in a diphenylthiazole (DPT)-induced rat model of PKD. DPT induces cystic change in all the collecting tubules, most severe in the outer medulla and inner cortex, and following withdrawal of DPT, cystic tubules return to normal with persistence of focal interstitial fibrosis. SDS-PAGE analyses of isolated tubular basement membranes (TBMs) of control and PKD kidneys revealed overall similar electrophoretic migratory bands. However, in PKD, there were relative increases in components with M(r) approximately 380,000, 250,000 and 145,000, and a decrease in the component with M(r) approximately 55,000. Immunoblot analyses revealed that the major components of TBM (type-IV collagen, laminin beta 1 and beta 2 chains and entactin) were present in the same relative concentrations in control and PKD. The expression of tubulointerstitial (TIN) antigen was decreased. Also, the relative concentrations of type-I collagen and fibronectin were increased in the PKD group. Following recovery, the expressions of TIN and fibronectin returned to normal, whereas type-I collagen remained elevated. ELISA determinations revealed increased expression of interstitial collagens type-I, -V and -VI in PKD vs control and they remained elevated following recovery, while that of type-III was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of electron microscopic immunocytochemistry to the human kidney: distribution of type IV and type VI collagen in normal human kidney.

We used immunogold electron microscopic (IEM) techniques with periodate-lysine-paraformaldehyde-fixed and Lowicryl-embedded or cryopreserved tissues to study the distribution of alpha 1(IV) and alpha 3(IV) chains of Types IV and VI collagen in glomerular basement membrane (GBM) and mesangial matrix of glomeruli in normal human kidneys. Monoclonal antibodies to alpha 1(IV) and alpha 3(IV) collagen chains and Type VI collagen could be detected only with cryoultramicrotomy, whereas polyclonal anti-Type IV collagen antibody was detectable in Lowicryl-embedded tissue. Ultrastructural detail was better preserved in the Lowicryl-embedded tissue. IEM labeling provided more detailed information as to the site-specific array of these extracellular matrix molecules in glomeruli than did immunofluorescent microscopy. The labeling of alpha 1(IV) collagen chain was distributed mainly along the endothelial side of glomerular basement membrane and the mesangial matrix. Mesangial GBM was relatively poorly labeled compared with that of mesangial matrix. In contrast, the alpha 3(IV) chain was detected throughout the thickness of the GBM, but there was no labeling of mesangial matrix. Type VI collagen distribution was identical to that of the alpha 1(IV) chain within the glomerulus but was also associated with interstitial collagen fibrils. This study documents and details the heterogeneous distribution of Type IV and VI collagen chains within the normal human glomerulus and provides the framework for the study of these matrix components in human glomerular diseases.

Glomerular distribution of type IV collagen in diabetes by high resolution quantitative immunochemistry.

We examined type IV collagen distribution and density in human diabetic kidneys by quantitative immunogold electron microscopy. We studied normal kidney transplant donors and "slow-track" and "fast-track" insulin dependent diabetic (IDDM) patients. The "slow-track" patients had IDDM for > or = 20 years and mesangial volume fraction (VvMes/glom) of < or = 0.32. The "fast-track" patients had IDDM for < or = 20 years and VvMes/glom > or = 0.37. Renal biopsies were embedded in Lowicryl, reacted with polyclonal anti-type IV collagen (in the distribution of the classical alpha 1(IV) and alpha 2(IV) collagen chains) and monoclonal anti-alpha 4(IV) collagen chain antibody followed by gold conjugated secondary antibody. We found, by morphometric techniques, a decrease in the immunogold densities of anti-type IV collagen in the subendothelial zone of the GBM in the "fast-track" IDDM patients. There was a trend towards a decrease in mesangial matrix (MM) particle density in the "fast-track" (P = 0.07) but not in the "slow-track" patients. However, because of the marked increase in MM in the "fast-track" patients, the per glomerulus estimated quantity of these antigens in MM was increased. In contrast, the density of alpha 4(IV) collagen chain was increased in the epithelial zone of the GBM in the "fast-track" IDDM patients. It is not known whether these changes in glomerular type IV collagen represent markers of advanced diabetic lesions or whether these changes might be detected earlier in diabetic patients destined for the later development of serious lesions.

Tubulointerstitial nephritis antigen interacts with laminin and type IV collagen and promotes cell adhesion.

Tubulointerstitial nephritis (TIN) antigen has been recently identified as a novel basement membrane macromolecule. It consists of a single chain of 58 kDa and exhibits a restricted distribution. The interaction between TIN antigen and laminin or type IV collagen has been studied using solid-phase binding assays and found to be for both macromolecules specific, saturable, and with an affinity in the low micromolar range. In similar assays, TIN antigen did not interact with heparin. In turbidimetry assays, it was found that the presence of TIN antigen did not affect the polymerization of type IV collagen but had a concentration-dependent inhibitory effect on laminin polymerization and on preformed laminin polymers. TIN antigen was able to promote adhesion of epithelial cells derived from kidney tubules and of endothelial cells derived from aorta. The data suggest that TIN antigen may be a macromolecule of importance both for basement membrane ultrastructure and cellular adhesion.

Immunochemical and biochemical evidence for distinct basement membrane heparan sulfate proteoglycans.

Two antigenically and structurally related heparan sulfate proteoglycans (HSPG), with masses of 200 and 350 kDa, have been isolated and characterized from bovine renal tubular basement membranes (BTBM) using DEAE-Sephacel, octyl-Sepharose CL-4B, and Propac PA-1 chromatography. Heparitinase treatment revealed core proteins of 145 and 125 kDa, with corresponding core proteins after trifluoromethanesulfonic acid treatment of 88 and 82 kDa, from the 200- and 350-kDa HSPGs, respectively. The separated HSPGs produced similar tryptic peptide maps, had similar amino acid compositions, and had similarly sized GAG chains. The 200-kDa HSPG had 2.1 mg of protein/mumol of hexuronic acid compared with 1.1 mg/mumol for the 350-kDa HSPG. Anti-BTBM HSPG monoclonal antibody (mAb A12) reacted with core proteins derived from the 200- and 350-kDa HSPGs, whereas anti-perlecan polyclonal and monoclonal antibodies did not bind to the BTBM HSPG core proteins described above but reacted with a 230-kDa core protein, which was nonreactive with mAb A12. Immunohistochemical studies of the kidney demonstrated differences in the distribution of BTBM HSPG and perlecan. Comparison of amino acid sequences from BTBM HSPG tryptic peptides with the sequence of perlecan revealed similarities but not extensive identity. Two tryptic peptides show homology to rat agrin, a basement membrane component of synaptic junctions. These data suggest that the two BTBM HSPGs are immunologically and structurally related and that differences in these molecules may arise from alternative splicing or posttranslational modifications. In addition, the two BTBM HSPGs are immunologically and structurally distinct from perlecan but may share homology with agrin.

The Goodpasture antigen: common epitopes in the globular domains of collagen IV.

To determine the nature of Goodpasture antibody-reactive epitopes on the globular domains of collagen IV [non collagenous (NC) domain], Goodpasture antigen was characterized by immunochemical and immunohistological techniques using affinity-purified (AP) Goodpasture autoantibodies. Affinity purification of Goodpasture autoantibodies toward alpha 1(IV), alpha 2(IV), and alpha 3(IV) NC domains was performed and revealed antigenic cross-reactivity with all alpha(IV) NC domain subunits, which was confirmed by inhibition ELISA. Since by immunofluorescent microscopy all 3 AP Goodpasture antibodies only stained the central portion (lamina densa) of bovine glomerular basement membrane, it appears that there are common epitopes reactive with Goodpasture autoantibodies present on alpha 1(IV) NC, alpha 2(IV) NC, and alpha 3(IV) NC domains.

Characterization of a non-Goodpasture autoantibody to type IV collagen.

Goodpasture's syndrome is a very severe and aggressive autoimmune kidney disease. The patients' autoantibodies, which are pathogenic, are restricted to the C-terminal region of the alpha 3-chain of type IV collagen. In this paper we characterize an anti-type IV collagen antibody from a patient with a non-progressive form of glomerulonephritis. ELISA and immunoblotting were used to study the specificity of this patient's antibodies. The patient had high titres of antibodies restricted to the C-terminal region of the alpha 1-chain of type IV collagen. The antibody recognized an epitope hidden in the NC1 molecule which was fully exposed after denaturation or reduction. It was an IgG3 antibody composed of only lambda light chains, indicating that it has a potential to induce inflammatory damage and that it is probably monoclonal. This patient also had MPO-ANCA which were of IgG1 subclass. Our patient had no disease progression during the 5 years of treatment. Even though the anti-alpha 1 (IV) antibodies react with the same domain, but of a different chain of type IV collagen compared to the Goodpasture's antibodies, they do not induce any severe damage. It is thus uncertain if the anti-alpha 1 (IV) antibodies have any pathogenic role; the kidney damage might have been caused by the MPO-ANCA. The findings support the theory that the anti-alpha 3 (IV) antibody causes disease in Goodpasture's syndrome and that antibodies restricted to other subunits of the C-terminal region of type IV collagen are less harmful.