The role of sulfatides in autoimmunity in children with various glomerular disease]

Previous studies have suggested that autoimmunity to a number of kidney antigens may exist in glomerular disease. Our own work suggested that sulfatide which is one of the major acidic glycolipids of human kidney may be antigenic. Glycolipids were isolated from lipid extract of human kidney using thin-layer chromatography (TLC). As the major acidic glycolipids, sulfatide, CDH-sulfate, GM3, GD3 were identified. Acidic fraction of lipid extract were chromatographed and then tested for antigen by immunostaining. Sera from patients with IgA nephropathy (IgAN) and Henoch-Sch?nlein purpura nephritis (HSPN) contained antibody to the sulfatide of human kidney as determined by the direct binding of antibody to TLC. In addition, we measured the presence of sulfatide antibodies by enzyme linked immunosorbent assay (ELISA) in sera of patients with various glomerular disease: IgAN, HSPN, mesangial proliferative glomerulonephritis, membranoproliferative glomerulonephritis (MPGN), focal and segmental glomeruosclerosis (FSGS), membranous nephropathy (MN), minimal change nephrotic syndrome (MCNS), acute post streptococcal glomerulonephritis (PSAGN), and lupus nephritis (LN). IgM class sulfatide antibody were demonstrated in many cases of them. The incidence of IgA class sulfatide antibody in HSPN and IgAN was significantly high, and also the high incidence of IgG class sulfatide antibody occurred in IgAN. On the other hand, we evaluated cellular hypersensitivity to sulfatide in IgAN, HSPN, and FSGS using an active E-rosette assay. Positive results occurred in IgAN and HSPN. It was suggested that delayed hypersensitivity to sulfatide may generate an autoimmune inflammatory process. It has been reported that laminin binds specifically to sulfatide. Autoimmunity to sulfatide may disturb the laminin binding and consequently interfere with renal function. These results suggested sulfatide antigen may play important role in occurrence and aggravation of glomerular disease.     

Synthesis of immunoglobulins against Haemophilus parainfluenzae by tonsillar lymphocytes from patients with IgA nephropathy.

BACKGROUND: We previously demonstrated glomerular deposition of Haemophilus parainfluenzae (HP) antigens and the presence of IgA antibody against HP antigens in patients with IgA nephropathy (IgAN). In this report we examine the synthesis of immunoglobulins against HP antigens in tonsillar lymphocytes from patients with IgAN. METHODS: We used tonsillar lymphocytes isolated from the palatine tonsils of 15 patients with IgAN and 16 patients with chronic tonsillitis but without renal disease. We examined lymphocyte proliferation and production of IgA, IgG, and IgM antibodies against HP antigens by measuring thymidine uptake and concentrations of these antibodies in culture supernatants after lymphocyte incubation with HP antigens by ELISA. RESULTS: Lymphocytes from patients with IgAN showed a significantly higher stimulation index (SI) on exposure to HP antigens (thymidine incorporation in tonsillar lymphocytes exposed to HP (c.p.m.)/ thymidine incorporation in unstimulated tonsillar lymphocytes (c.p.m.)) than did controls (P=0. 0015). Lymphocytes from patients with IgAN also showed a significantly higher IgA SI (concentrations of IgA against HP antigens in supernatants from HP-stimulated lymphocytes/IgA against HP antigens in supernatants from unstimulated tonsillar lymphocytes) than did controls (P=0.0004). We found positive correlations between concentrations of IgA and IgG antibodies, between IgA and IgM antibodies, and between IgG and IgM antibodies against HP antigens after HP stimulation. CONCLUSIONS: Our results suggest that HP antigens stimulate tonsillar T and B lymphocytes in patients with IgAN and that these patients have polyclonal activation of lymphocytes against HP antigens, with isotype switching of antibody production from IgM to IgA.     

Lack of antibody production against Hanganutziu-Deicher (H-D) antigens with N-glycolylneuraminic acid in patients with porcine exposure history

The significance of non-alphagalactosyl antigens remains unclear in pig-to-primate xenotransplantation. Hanganutziu-Deicher (H-D) antigens with terminal N-glycolylneuraminic acid (NeuGc) are widely expressed on endothelial cells of mammalian species, with the exception of humans. As baboons and monkeys also express H-D antigens, a pig-to-non-human primate experimental model cannot resolve the question of whether H-D antigens can elicit a potent humoral response in human recipients. The purpose of this study was to elucidate the clinical significance of H-D antigens by examining the sera from patients who have been previously exposed to porcine tissue. After the digestion of porcine aortic endothelial cells (PAEC) by neuraminidase, NeuGc and N-acetylneuraminic acid (NeuAc) were quantitated by HPLC. IgG and IgM antibody levels against H-D antigens were measured by NeuGc-GM3-coated ELISA plates in the sera of patients who had undergone ex vivo kidney perfusion 1 to 3 weeks and 2 years previously (n=2) or had been injected with fetal porcine islets 2 months previously (n= 10). HPLC determined that 9.7x 10(7) NeuAc and 6.3x 10(7) NeuGc residues per cell were released from PAEC by neuraminidase, while 25.7x 10(7) NeuAc and an undetectable level of NeuGc were released from human aortic endothelial cells (HAEC). No significant elevation of IgG or IgM antibody levels against NeuGc-GM3 was observed in sera from patients with a history of porcine exposure. Considering the active production of antibody against the foreign galactosyl antigens after pig-to-human xenotransplantation, some production of antibodies against the equally foreign H-D antigens would be expected, because large amounts of NeuGc terminated saccharides are present in the pig endothelial cell surface. However, no production of antibodies directed to H-D antigens could be found in patients exposed to porcine tissue. Further studies are warranted to explain why H-D antigens do not elicit a significant antibody production.     

Antiglomerular basement membrane antibody: antibody specificity in different forms of glomerulonephritis

Components were solubilized from human glomerular basement membrane by digestion with collagenase and pepsin or by extraction with guanidine-HCl either directly or after previous digestion with the enzyme. The diverse preparations were used as antigens in the enzyme-linked immunosorbent assay (ELISA) of antibody titers in sera from patients with Goodpasture syndrome and patients with other forms of glomerulonephritis, that is, systemic lupus erythematosus, periarteritis nodosa, and IgA-related nephropathy. Patients with Goodpasture syndrome had high titers of IgG antibodies reacting most strongly with collagenase digests. The antigen(s) was only partly solubilized by guanidine-HCl extraction, was destroyed by pepsin digestion as well as reduction, and partly destroyed by trypsin digestion. The antigen(s) is most likely noncollagenous protein. Antibodies from patients with other forms of nephritis were directed primarily against antigens in guanidine-HCl extracts, while the antigen(s) was not solubilized by collagenase digestion. Pepsin digestion destroyed the antigen(s). The antibodies were of a different class, that is, the patients with systemic lupus erythematosus had IgG and IgA as well as IgM antibodies; the patients with periarteritis nodosa had IgM or IgG and IgA antibodies, while the patients with IgA-related nephritis had the highest recorded titers of IgA but also had IgG as well as IgM antibodies. None of the patients had antibodies directed against triple helical collagen. The antibody response in anti-GBM antibody-related nephritis, then, is different both with respect to antigen and antibody class and depends on the underlying disease syndrome.     

Non-Goodpasture anti-GBM antibodies in patients with glomerulonephritis

The sera of 206 consecutive patients with biopsy-proven glomerulonephritis were tested by ELISA for the presence of Goodpasture and non-Goodpasture anti-GBM antibodies. Antigens were solubilised from human GBM with purified bacterial collagenase and with 6 mol/l guanidine-HCl respectively. Only 12 sera reacted when collagenase-resistant GBM proteins were used as antigens in ELISA. Sera from two of these patients also reacted with the Goodpasture antigen, that is the globular domain of collagen IV, purified from collagenase extracts of GBM. These two patients had classical Goodpasture syndrome with linear crescentic nephritis. The other ten sera did not react with the Goodpasture antigen and immunofluorescence microscopy showed granular glomerular immune deposits. Antibodies against antigens present in 6 mol/l guanidine-HCl extracts of human GBM were much more frequent, particularly in lupus nephritis and IgA nephropathy, but relatively common also in patients with glomerulonephritis associated with systemic connective tissue and systemic vasculitic disorders. In contrast, these non-Goodpasture antibodies were only sporadic in primary forms of glomerulonephritis such as minimal-change nephropathy, membranous glomerulopathy, or acute post-infectious glomerulonephritis. The presence of circulating IgG, IgA or IgM antibodies against 6 mol/l guanidine-HCl extractable GBM antigens correlated with granular deposits of corresponding immunoglobulins in both mesangial and capillary loop regions of glomeruli, indicating a possible pathogenic role for non-Goodpasture anti-GBM antibodies in several forms of glomerulonephritis.     

Serum levels of galactose-deficient IgA in children with IgA nephropathy and Henoch-Schönlein purpura

IgA nephropathy and Henoch-Schönlein purpura nephritis (HSPN) are related diseases characterized by deposits of IgA1-containing immune complexes in the renal mesangium. Adult patients with IgA nephropathy have aberrantly glycosylated IgA1 (galactose-deficient O-linked glycans) in the circulation and renal deposits. However, IgA1 glycosylation has not been studied in pediatric patients with IgA nephropathy. Using our quantitative lectin enzyme-linked immunosorbent assay (ELISA) test, we measured serum levels of galactose-deficient IgA1 of children with IgA nephropathy and HSPN and controls. Children with IgA nephropathy and HSPN had serum levels higher than those of healthy children or renal-disease controls with C1q nephropathy. Furthermore, lectin ELISA identified patients with HSPN whose clinical course mimicked that of IgA nephropathy. In summary, pediatric patients with IgA nephropathy and HSPN have an aberrancy in the glycosylation in IgA1 O-linked glycans that is similar to that in adults with IgA nephropathy.     

IgM/IgA nephropathy in callitrichids: antigen studies.

Renal tissues of callitrichids with IgM nephropathy were immunohistochemically examined for the participation of IgA in pathogenesis. In 58 histopathologically nephropathy-positive kidneys, IgM predominated in 20 cases and IgA in 7 cases, and in 31 cases both immunoglobulins were rated to be approximately equally involved. The disease, therefore, might be described as IgM/IgA nephropathy. The renal tissues and sera were also tested for nutritional antigens or antinutritional antigen antibodies, using immunohistochemistry and Western blots (tissues) and enzyme-linked immunosorbent assay (sera). Evidences of nutritional antigens in the renal tissues were inconclusive, although circulating IgG class antibodies against cereals, milk, and egg proteins were present in quite a number of sera. Particular consideration was paid to IgA-antigliadin antibodies, which were statistically significantly associated with nephropathy as were IgA rheumatoid factors. The findings are discussed in relation to human IgA and IgM nephropathies.     

Staphylococcus aureus cell envelope antigen is a new candidate for the induction of IgA nephropathy

BACKGROUND: IgA nephropathy is the most common form of glomerulonephritis worldwide. We previously reported a novel form of glomerulonephritis with glomerular IgA deposits following methicillin-resistant Staphylococcus aureus (S. aureus) infection. We investigated the role of S. aureus related antigens in the immunopathogenesis of IgA nephropathy by producing several monoclonal antibodies against S. aureus surface antigens and determining the epitopes of deposited antigens in patients with IgA nephropathy. METHODS: Cell membrane proteins were isolated from cultured S. aureus. Mouse monoclonal antibodies against these proteins were generated, and their target epitopes were determined by antibody affinity chromatography and amino acid sequence analysis, and by monoclonal antibody screening of Escherichia coli clones transfected with plasmids from the Lambda S. aureus Genomic Library. Renal biopsy specimens from 116 patients with IgA nephropathy and 122 patients with other forms of renal disease were examined for glomerular antigen depositions by immunofluorescence microscopy. RESULTS:. The major antigen recognized by monoclonal antibodies against S. aureus cell membrane was identified as the S. aureus cell envelope antigen designated 'probable adhesin' (ACCESSION AP003131-77, Protein ID; BAB41819.1). In 68.1% (79/116) of renal biopsy specimens from patients with IgA nephropathy, S. aureus cell envelope antigen was localized in the glomeruli, and the data confirmed that S. aureus cell envelope antigen was co-localized with IgA antibody in the glomeruli. No deposition of this antigen was detected in the glomeruli of patients with non-immune complex deposit forms of glomerulonephritis. CONCLUSION: S. aureus cell envelope antigen is a new candidate for the induction of IgA nephropathy.     

Serum immunoglobulin levels and natural antibodies to Haemophilus influenzae in hemodialysis patients: evidence for IgG subclass imbalances

Humoral immune parameters were studied in 13 patients with end-stage renal failure on maintenance hemodialysis. Serum IgA, IgM and IgG concentrations were comparable to control values from 14 healthy blood donors. IgG subclass analysis revealed significantly increased IgG1 levels in the patients when compared to controls (p less than 0.01). In 3 patients, IgG2 deficiency was found, in one case associated with low IgG3 level. Concentrations and subclass composition of naturally occurring antibodies to Haemophilus influenzae type b (Hib) polysaccharide (PS) were measured using an indirect ELISA. In patients IgM and IgG, including IgG1 and IgG2 antibodies to Hib, presented no difference from controls. Subclass analysis of Hib specific IgG antibodies revealed that IgG2 accounted for a substantial amount of the anti-Hib PS antibody response in controls as well as in patients. We conclude that patients on maintenance hemodialysis present imbalances of immunoglobulin levels. However, the antibody response to certain PS antigens could remain unaffected by renal failure.     

Circulating anti-entactin antibodies in patients with glomerulonephritis

Sera from 305 consecutive patients in a renal biopsy series were analyzed for the presence of anti-entactin antibodies by ELISA. Of these patients, 59% had primary glomerulonephritis, 21% had secondary glomerulonephritis, while 20% had other nephropathies (noninflammatory conditions like amyloidosis, diabetic nephropathy, nephrosclerosis, etc.). Forty-one of these patients (13.4%) were positive for IgG/IgM antibodies against entactin: 60% of them had primary glomerulonephritis, 35% had secondary glomerulonephritis, while the remaining 3 patients had other nephropathies. Fifteen (70%) of the 23 patients with primary glomerulonephritis had proliferative glomerulonephritis (PGN), whereas 13 (87%) of the 15 patients with secondary glomerulonephritis were due to systemic connective tissue diseases (SCTD): 7 due to SLE, 4 due to SLE like SCTD and two due to other SCTD. There was a peak of incidence corresponding to the group aged 18 to 30 years. A majority of these patients (12 of the total 17) had primary glomerulonephritis and were associated with nephrotic or subnephrotic grade proteinuria, poorly or nonresponsive to immunosuppressive treatment and associated, in several cases, with progressive deterioration of renal function. In addition, there was a tendency to another peak in the age group 51 to 60 years. Most of these patients (6 of the total 8) had glomerulonephritis secondary, mainly, to SLE or SLE like SCTD with milder degree of proteinuria and better preserved renal functions. Anti-entactin antibodies were not found in certain glomerulonephritides like IgA nephropathy and those secondary to systemic vasculitides and in control subjects (healthy subjects, and patients with a variety of non-renal disorders including inflammatory diseases).(ABSTRACT TRUNCATED AT 250 WORDS)     

Primary antiphospholipid antibody syndrome and mesangial IgA glomerulonephritis

The antiphospholipid antibody syndrome (APS) is characterized by recurrent thrombosis, fetal loss, multiorgan involvement, and the presence of lupus anticoagulant and/or anticardiolipin antibody. When not associated with systemic lupus erythematosus, other collagen diseases, or ingestion of medications, the condition is called primary APS. The kidney may be involved in the APS syndrome with acute nephritis and renal failure. The cases with renal biopsy studies have shown variable glomerular morphology, ranging from mild mesangial changes to a diffuse endocapillary proliferative glomerulonephritis. The most frequent lesion is thrombotic microangiopathy or features seen in the hemolytic uremic syndrome. Apart from fibrin thrombus deposition, only a few cases have shown focal and segmental deposits of IgG and/or IgM and/or C3. We describe a patient with primary APS who had thrombosis with lower limb amputation and acute renal failure. The renal biopsy specimen showed a focal proliferative glomerulonephritis with endothelial proliferation and damage, with diffuse heavy mesangial deposits of IgA and fibrinogen. This case with diabetes mellitus, but without diabetic nephropathy, represents the occurrence of primary APS and mesangial IgA nephropathy which potentiated the renal injury, leading to acute renal failure. The relationship to the Henoch-Sch?nlein syndrome is discussed.     

Glomerular deposition of mannose-binding lectin in human glomerulonephritis.

BACKGROUND: Mannose-binding lectin (MBL), a member of the collectin family, binds to various oligosaccharides and activates the classical pathway of complement independent from C1q. At present it is unknown whether this so-called lectin pathway of complement activation plays a role in the pathogenesis of human glomerulonephritis. METHODS: Direct immunofluorescence of 84 renal biopsies using an MBL-specific monoclonal antibody and antibodies directed against IgG, IgA, IgM, C1q, C3, and terminal complement complex (TCC) was performed. Serum MBL levels of 50 patients were determined by enzyme-linked immunosorbent assay. RESULTS: MBL was detected in the glomeruli of patients with lupus nephropathy (15 of 16), membranous nephropathy (10/15), membranoproliferative glomerulonephritis type I (5/6) and anti-GBM nephritis (2/4). MBL deposition paralleled that of immunoglobulins, C1q, C3, and TCC but was less intense as compared to C1q. Focal segmental deposits of MBL were present in focal segmental glomerulosclerosis (4/6), IgA nephropathy (3/11), amyloidosis AL (1/4), and advanced renal fibrosis (2/2). Here MBL staining was identical to IgM and C3 and considered an unspecific entrapment of MBL in sclerotic lesions in these cases. No significant difference in MBL serum levels was observed between normal controls and patients with lupus nephritis, membranous nephropathy, membranoproliferative glomerulonephritis, focal segmental sclerosis, minimal change disease or IgA nephropathy. In patients suffering from membranous nephropathy with (n=10) or without (n=5) glomerular MBL deposits serum creatinine, C3, C4, serum protein, and proteinuria were not statistically different. CONCLUSION: MBL is present in the glomeruli of patients with glomerulonephritis involving deposition of IgG and activation of the classical pathway of complement. We propose that MBL binds to agalactosyl oligosaccharides of IgG that terminate in N-acetylglucosamine. The extent to which the lectin pathway of complement contributes to overall complement activation in the glomeruli remains unknown, but is likely to be marginal.     

Experimental nephropathy induced by Haemophilus parainfluenzae antigens

BACKGROUND: We have demonstrated that outer membrane antigens of Haemophilus parainfluenzae (OMHP) are potentially involved in IgA nephropathy (IgAN). In this study, we established an experimental model of IgAN using OMHP antigens and investigated the nephritogenicity of OMHP antigens. METHODS: One hundred and twenty C3H/HeN mice were administered OMHP antigens orally (PO group) or intraperitoneally (IP group). Mice were sacrificed at 10, 20, 30, 40, and 50 weeks of age to examine sequential glomerular changes and to measure levels of IgG, IgA, and IgM antibody against OMHP by ELISA. RESULTS: Glomerular deposition of IgA and increases in the amount of mesangial matrix were observed in the PO group and the IP group from 40 and 30 weeks of age, respectively. Mice in both groups showed glomerular deposition of OMHP antigens from 30 or 40 weeks of age. Levels of IgA antibodies against OMHP were significantly increased in the PO and IP groups compared with controls. There was a significant correlation between mesangial proliferation and glomerular deposition of IgA. CONCLUSIONS: Administration of OMHP antigens to mice may induce glomerular deposition of IgA and mesangial proliferation, resembling the changes seen in IgAN, with increases in IgA antibodies against OMHP antigens. This is the first use of OMHP antigens to establish an active model of IgAN.     

Occurrence of anti-C1q antibodies in IgA nephropathy

Background: The pathogenic mechanisms and the antigens involved in the establishment and progress of IgA nephropathy are unknown. As antibodies against C1q have been reported to correlate with SLE nephritis, we analysed the occurrence of these antibodies in IgA nephropathy in order to investigate the possibility of pathogenetic similarities in these renal disorders. Methods: The occurrence of IgA- and IgG anti-C1q antibodies (anti-C1q) were determined by ELISA in patients with IgA nephropathy (n=36) and SLE nephritis (n=37), diseases both known to be associated with circulating immune complexes. Levels of these antibodies were also determined in two other glomerular diseases, i.e. idiopathic membranous glomerulo-nephritis (n=7) and minimal change disease (n=2), in which circulating immune complexes are usually not present, and in 40 healthy controls. Results: IgA anti-C1q was observed in increased titres in 11/36 of the patients with IgA nephropathy, in 2/37 of the patients with SLE nephritis (both with proliferative disease) and in 1/9 of the patients with membranous and minimal change disease (P<0.001). Increased titres of IgG anti-C1q were observed in 1/36 of the patients with IgA nephropathy, in 17/37 of the patients with SLE nephritis and in 0/9 of the patients with membranous and minimal change disease (P<0.001). There were no correlations between the levels of anti-C1q antibodies and clinical parameters such as degree of proteinuria, haematuria, or renal function. Nor was there any correlation to the concentration of C3a and the terminal complement complex (TCC) in patients with IgA nephropathy. Conclusions: The occurrence of anti-C1q antibodies in both IgA nephropathy and SLE nephritis, albeit of different predominating isotypes, indicates the possibility of a similar pathogenic mechanism involved in these renal disorders. The occurrence of IgA anti-C1q antibodies in patients with IgA nephropathy has to our knowledge not previously been reported.     

Assay of GBM antigen in urine and serum with an anti-human renal monoclonal antibody

Using a monoclonal antibody (Mab-G3) recognizing glomerular basement membrane (GBM), we assayed GBM antigen (G3-Ag) in the urine and serum of renal disease patients by sandwich ELISA. The subjects included normal control (NOR), minimal change nephrotic syndrome (MCNS), IgA nephropathy (IgA), membranous nephropathy (MN), membranoproliferative glomerulonephritis (MPGN) and chronic renal failure (CRF). The urine and serum was used as the material. With urinary G3-Ag, there were no statistically significant differences among the NOR, MCNS, IgA, MN, MPGN and CRF groups. Although no correlation was observed with proteinuria, hematuria, serum creatinine, serum beta 2 microglobulin and urinary NAG, urinary G3-Ag showed a significant (p less than 0.05) increase in excretion in the group of progressive CRF patients with s-Cr more than 1.0 mg/dl/month as compared to the stationary CRF group with s-Cr less than 1.0 mg/dl/month. Serum G3-Ag showed lower values in almost all cases, and there were no significant differences among the renal disease groups. The above findings led us to believe that the assay of urinary G3-Ag was useful in determining the degree of GBM disorder. It was also presumed that assay of renal antigens in urine and serum with the respective anti-human renal monoclonal antibodies could be a new tool in diagnosing renal diseases.     

Glomerular deposition of cross-linked fibrin in human kidney diseases

The immunofluorescent localization of cross-linked fibrin (XFb) in kidneys from 87 patients with renal diseases was evaluated using a monoclonal antibody that discriminates XFb from fibrinogen and its derivatives. Glomerular deposition of XFb, along the endothelial surface and in the mesangium, was frequently observed in patients with IgA nephropathy, Henoch-Sch?nlein purpura nephritis (HSPN), lupus nephritis, and hemolytic uremic syndrome (HUS), which was confirmed by immunoelectron microscopy. Dual-label immunofluorescent studies showed that XFb was deposited in limited areas among the sites reactive with anti-fibrinogen antibodies; XFb was not present in the crescents, Bowman's capsule or interstitium. The localization of XFb was generally discordant with that of the platelet membrane antigen and von Willebrand factor (factor VIII-related) antigen. Subendothelial co-deposition of XFb and immunoglobulins (IgA with or without IgG) occasionally accompanying C3 was found in the glomeruli of some of the patients with IgA nephropathy and HSPN. The distribution of XFb observed by immunoelectron microscopy was similar to that of electron dense deposits. The glomerular population of monocytes/macrophages in patients with XFb deposition was similar to that of those without deposition. Urinary XFb derivatives were detected by the latex agglutination test in three of the 16 patients with glomerular XFb deposition, and in two of the 18 patients without it. These data indicate that the coagulation system is activated in the kidney of patients with IgA nephropathy, HSPN, lupus nephritis and HUS, and support the concept that glomerular fibrin deposition is associated with endothelial/subendothelial and mesangial injury. The activation of the coagulation system in IgA nephropathy and HSPN seems to be mediated by immune complexes rather than monocytes/macrophages. Determination of urinary XFb derivatives is not helpful for assessing glomerular XFb deposition.     

Oral challenge with cow's milk in patients with IgA nephropathy--estimation of serum antibodies to cow's milk protein]

The author investigated the serum levels of antibodies against casein, beta-lactoglobulin and lactalbumin before and after challenging with cow's milk in 35 patients with IgA nephropathy, 18 with primary glomerulonephritis except for IgA nephropathy (GN control) and 11 healthy volunteers (H control). Blood samples were obtained at fasting, and at 30, 60, 120 and 180 min after oral challenging with 400 ml of cow's milk. IgA and IgG anti-cow's milk proteins antibodies were analyzed by ELISA. The same challenge was tested after administration of the antiallergic agent, sodium cromoglycate (SCG), in 11 patients with IgA nephropathy and 4 H controls. Serum levels of IgA anti-casein, -beta-lactoglobulin and lactalbumin antibodies in patients with IgA nephropathy were significantly higher than in control groups before challenging. However, those of IgG antibodies were not. The percent change of antibody titer after challenging with cow's milk did not elevate in any group, except for the level of IgA anti-beta-lactoglobulin antibody at 60 min in IgA nephropathy. Cases in which challenging produced marked elevation above the M + 2SD of the levels found in H control were expressed as "positive". The number of "positive" cases was 16 (45.7%) with IgA nephropathy, but none with GN control. There was no significant correlations between "positive" and "negative" cases with IgA nephropathy in clinical manifestations. In 3 out of 4 "positive" patients with IgA nephropathy, the levels of IgA antibody were suppressed after administration of SCG. It is concluded that the serum levels of IgA antibodies against cow's milk proteins are significantly elevated in IgA nephropathy, and are inhibited in elevation after oral challenge with cow's milk by administration of an antiallergic agent in some patients with IgA nephropathy.     

Antimouse laminin antibodies in IgA nephropathy and various glomerular diseases.

IgG, IgA and IgM class antibodies to mouse laminin and human fibronectin in sera from patients with various glomerular diseases (50 cases of IgA nephropathy, 5 cases of minimal-change nephrotic syndrome; 6 cases of membranous nephropathy, 5 cases of systemic lupus erythematosus, 2 cases of Henoch-Sch?nlein purpura, 3 cases of poststreptococcal nephritis and 4 cases of preeclampsia) and from 30 normal controls were tested using a solid-phase enzyme-linked immunosorbent assay method. IgA antimouse laminin antibody titers in sera from IgA nephropathy patients were significantly higher (p less than 0.05) than in controls. There were no statistical differences in IgA antimouse laminin antibody titers between patients with other glomerular diseases and normal controls. IgM antimouse laminin antibody was significantly raised (p less than 0.01) in sera from patients with preeclampsia. The reaction of mouse laminin with the IgA nephropathy and preeclampsia sera on each of the IgA and IgM assay systems was inhibited by the antigen at up to 5 micrograms/ml. However, it was not inhibited by anti-C3d, anti-C1q, anti-J chain and antisecretory component sera or saccharides. The reaction of mouse laminin with an exceptionally high-titer IgA antimouse laminin antibody serum from a normal control on the IgA assay system was clearly inhibited by 1 mM of melibiose, which contains alpha-galactosyl residues. The same concentration of melibiose, however, did not inhibit the reaction of mouse laminin with IgA nephropathy sera on the same assay system. Treatment of mouse laminin with alpha-galactosidase did not alter any binding from IgA nephropathy sera but binding was lost from an exceptionally high-titer normal control serum. There were no correlations between serum IgA level and IgA antimouse laminin antibody titer in sera from IgA nephropathy patients. Immunoblot techniques revealed the presence of antibody in sera from IgA nephropathy patients reacting with both subunits A and B of laminin, somewhat stronger with laminin A. None of the sera tested contained antifibronectin antibodies. These results indicate that the IgA antimouse laminin antibody is a specific antibody in IgA nephropathy and might play a role in the pathogenesis of the nephritis since mouse laminin and human mesangial laminin present a common epitope.     

Monocyte infiltration and cross-linked fibrin deposition in IgA nephritis and Henoch-Schoenlein purpura nephritis

To clarify the role of immune cell infiltration and fibrin deposition in glomerular injury, renal biopsy specimens taken from patients with primary IgA nephritis and Henoch-Sch?nlein purpura nephritis (HSPN) were evaluated using monoclonal antibodies specific to mononuclear cell surfaces and cross-linked fibrin (XFb). Monocytes/macrophages were the predominant cell type infiltrating glomeruli in IgA nephritis and HSPN. The intraglomerular monocyte population in both diseases was significantly higher than that in normals, mesangial proliferative (non-IgA) glomerulonephritis or minimal change nephrotic syndrome. In IgA nephritis, there was a clear correlation between glomerular monocyte accumulation and the degree of proteinuria. Although the monocyte influx tended to decline with time in HSPN, it remained unchanged in IgA nephritis. XFb deposition was found in the glomeruli of 27 out of 48 patients with IgA nephritis, and in 15 out of 20 with HSPN. The degree of XFb deposition in IgA nephritis correlated significantly with the degree of mesangial proliferation. These findings indicate a close relationship of monocyte/macrophage infiltration and XFb deposition with glomerular injury in IgA nephritis.