Detection Of anti-GBM Antibodies Research Articles

Subsequent COVID-19 Prophylaxis in COVID-19 Associated Glomerulopathies.

Successful vaccination has been the decisive factor in the overall decline of SARS-CoV2 infection related morbidity and mortality. However, global effects of the COVID-19 pandemic are ongoing, with reports of glomerular disease occurring in relation to both infection and vaccination. A particular rise in anti-GBM disease has been identified. Information is still emerging regarding the optimal management of such cases. We reviewed anti-GBM antibody detection rates at our test center over the past 5 years. We followed three patients with biopsy confirmed glomerular disease temporally related to COVID-19 vaccination. Each patient proceeded to receive subsequent COVID-19 vaccination as per immunologist recommendations. Further assessment included COVID-19 antibody testing in each case. A three-fold increase in significant anti-GBM antibody results noted at our center was associated with COVID infection in 10% of cases, and COVID vaccination in 25% of cases. We demonstrated that subsequent vaccination did not appear to lead to adverse effects including relapse in our three cases of COVID-19 vaccine-associated GN. We also identified positive COVID-19 antibody levels in two out of three cases, despite immunosuppression. We report a rise in anti-GBM antibody disease incidence. Our small study suggests that COVID-19 antibody testing can help determine COVID prophylaxis requirements, and subsequent vaccination with an alternative vaccine type appears safe.

Evaluation of the diagnostic performance of an immunoblot for ANCA and anti-GBM antibody detection

The use of high-quality antigen-specific immunoassays for detecting anti-neutrophil cytoplasmic antibodies (ANCA) and anti-glomerular basement membrane (GBM) autoantibodies is recommended in patients with suspected ANCA vasculitis and/or anti-GBM disease. We analysed the diagnostic performance of a semi-quantitative and rapid immunoblot (EUROIMMUN AG, Lübeck, Germany) in two settings. Patient sera from different cohorts (ANCA vasculitis n = 187, anti-GBM disease n = 19, and disease controls n = 51) were used. The diagnostic performance of the immunoblot was assessed when used as a confirmatory test for the presence of ANCA in suspected ANCA vasculitis and when evaluating the presence of ANCA and/or anti-GBM antibodies in AAV and/or anti-GBM disease patients with a rapidly progressive glomerulonephritis (RPGN). In a confirmatory test setting, the immunoblot had an optimal sensitivity and specificity of 97.4 and 98.1% for PR3-ANCA and 98.5 and 96.4% for MPO-ANCA, respectively. With increasing test result ranges, a higher interval likelihood ratio (LR) was found for both ANCA entities. When evaluating for ANCA in patients with RPGN, the highest diagnostic accuracy (sensitivity 92.9% and specificity 100%) was obtained by using different cut-off values of positivity for PR3- (>5) and MPO-ANCA (>10). Also, the diagnostic performance for detecting anti-GBM was good (sensitivity 100% and specificity 100%). There are advantages over other assays in terms of time, costs, and interpretation of results. The immunoblot is a useful addition to current guidelines, particularly when a rapid diagnosis is necessary.

Comparison of the performance of a chemiluminescence assay and an ELISA for detection of anti-GBM antibodies

Objective Autoantibodies to the α3 chain noncollagen 1 domain of type IV collagen (α3(IV)NC1) are a serological hallmark in the diagnosis of anti-glomerular basement membrane (GBM) disease. The objective of our study was to compare the performance of anti-glomerular basement membrane (GBM) antibody detection by chemiluminescence immunoassay (CIA) and by enzyme-linked immunosorbent assays (ELISAs). Methods Sera from outpatients who were suspected to have anti-GBM disease and 31 patients with biopsy-proven anti-GBM disease were collected. Thirty normal controls were also included. All samples were tested for anti-GBM antibodies by CIA and commercial ELISA. The anti-GBM antibody-positive samples were confirmed by a homemade ELISA coated with recombinant human α3(IV)NC1. Results Compared with detection of anti-GBM antibodies with ELISA, detection of anti-GBM antibodies with CIA showed a positivity agreement of 70% and a negativity agreement of 98.6%. Among the 4 patients with different results, the anti-GBM antibody detection by CIA was in agreement with the homemade ELISA coated with recombinant human α3(IV)NC1 and the clinical diagnosis. In 31 patients with anti-GBM disease, good agreement was achieved in the detection of anti-GBM antibodies with CIA, commercial ELISA and the homemade ELISA (100%, 100%). The AUC for CIA and commercial ELISA was 0.987 and 0.966, respectively. Conclusions The detection of anti-GBM antibodies with CIA demonstrated good sensitivity and specificity and was in good agreement with our homemade ELISA, which seems better than the commercial ELISA in suspected anti-GBM disease patients. The three assays performed in parallel in the diagnosis of anti-GBM disease patients.

Recurrence of Goodpasture syndrome without circulating anti-glomerular basement membrane antibodies after kidney transplant, a case report

BackgroundGoodpasture Syndrome (GS) is an autoimmune disease caused by the development of auto-antibodies against the Glomerular Basement Membrane (GBM). Linear deposit of immunoglobulins G on the GBM detected by immunofluorescence analysis of renal biopsies is a GS pathognomonic finding. GS is commonly monophasic and its incidence is 1.6 case per million per year.Case presentationThis report describes and discusses the case of a 40-year-old woman who one year after allograft kidney transplant, presented with acute pulmonary and renal symptoms of GS, leading to acute graft dysfunction, without circulating anti-GBM antibody detection in laboratory assays. She received a living donor kidney transplant 4 years after the first diagnosis of GS without circulating anti-GBM antibodies, when considered in remission.ConclusionsIn both episodes, the diagnosis of GS was based exclusively on the kidney biopsy that showed rapidly progressing glomerulonephritis with deposition of immunoglobulins G on the GBM. Although rare, the management of patients with GS without circulating anti-GBM antibodies is difficult due to the lack of standardized follow-up guidelines to reduce the risk of GS recurrence after kidney transplantation.

Diagnosis and classification of Goodpasture's disease (anti-GBM)

Goodpasture's disease or anti-glomerular basement membrane disease (anti-GBM-disease) is included among immune complex small vessel vasculitides. The definition of anti-GBM disease is a vasculitis affecting glomerular capillaries, pulmonary capillaries, or both, with GBM deposition of anti-GBM autoantibodies. The disease is a prototype of autoimmune disease, where the patients develop autoantibodies that bind to the basement membranes and activate the classical pathway of the complement system, which start a neutrophil dependent inflammation. The diagnosis of anti-GBM disease relies on the detection of anti-GBM antibodies in conjunction with glomerulonephritis and/or alveolitis. Overt clinical symptoms are most prominent in the glomeruli where the inflammation usually results in a severe rapidly progressive glomerulonephritis. Despite modern treatment less than one third of the patients survive with a preserved kidney function after 6 months follow-up. Frequencies vary from 0.5 to 1 cases per million inhabitants per year and there is a strong genetic linkage to HLA-DRB1∗1501 and DRB1∗1502. Essentially, anti-GBM disease is now a preferred term for what was earlier called Goodpasture's syndrome or Goodpasture's disease; anti-GBM disease is now classified as small vessel vasculitis caused by in situ immune complex formation; the diagnosis relies on the detection of anti-GBM in tissues or circulation in conjunction with alveolar or glomerular disease; therapy is effective only when detected at an early stage, making a high degree of awareness necessary to find these rare cases; 20–35% have anti-GBM and MPO-ANCA simultaneously, which necessitates testing for anti-GBM whenever acute test for ANCA is ordered in patients with renal disease.

Performance evaluation of a novel chemiluminescence assay for detection of anti-GBM antibodies: an international multicenter study

Autoantibodies to the non-collagen region (NC1) of the alpha-3 subunit of collagen IV represent a serological hallmark in the diagnosis of Goodpasture's syndrome (GPS). The objective of our study was to carefully analyze the performance characteristics of a novel anti-glomerular basement membrane (GBM) chemiluminescence immunoassay (CIA). Sera from patients with GPS (n = 90) were collected from four clinical centers. Samples from different disease groups (n = 397) and healthy individuals (n = 400) were used as controls. All samples were tested for anti-GBM antibodies by a rapid, random access CIA (QUANTA Flash™ GBM). Most of the samples were also tested using other methods including different commercial anti-GBM IgG assays and research assays for anti-GBM IgA and IgM. The sensitivity and specificity of the novel CIA was 95.6% [95% confidence interval (CI) 89.0-98.8%] and 99.6% (95% CI 98.9-99.9%), respectively. Receiver operating characteristic analysis showed good discrimination between GPS patients and controls. The area under the curve was 0.98 (CI 0.96-1.0). The three anti-GBM antibody-positive samples from the control group were from two healthy individuals and one human immunodeficiency virus (HIV)-infected patient. All three individuals had low levels of anti-GBM antibodies [20, 24 and 25 chemiluminescent unit (CU), cutoff 20 CU]. When the results of the new CIA were compared to other methods, good agreement was observed: 95.8% (kappa = 0.92) versus EliA™ GBM, 97.4% (kappa = 0.95) versus both BINDAZYME™ Anti-GBM and QUANTA Lite® GBM. Anti-GBM IgA was detectable in low concentrations in patients with GPS and was associated with anti-GBM IgG but was less useful in discriminating GPS patients and controls. No discrimination was found for anti-GBM IgM. The novel QUANTA Flash™ GBM CIA demonstrated good sensitivity and specificity and had good agreement with other methods. Our data confirm that ∼5% of patients with GPS do not have detectable levels of anti-GBM antibodies.

IgA Deposits Along Glomerular Basement Membranes in Rapidly Progressive Glomerulonephritis

This case presents a rare type of crescentic glomerulonephritis characterized as IgA deposits predominantly along the glomerular basement membranes (GBM). The patient clinically manifested with rapidly progressive glomerulonephritis (RPGN) without pulmonary hemorrhage or vasculitis-related systematic symptoms. No positive results were found on antinuclear antibody (ANA), antineutrophil cytoplasmic antibody (ANCA), or anti-GBM antibody detection. Therapy with pulse methylprednisolone and intravenous cyclophosphamide was less effective. This case does not belong to the present three categories of crescentic glomerulonephritis based on the clinical characteristics, serum test, immunofluorescence, and electron microscopic findings.

Evaluation of the FIDIS Vasculitis Multiplex Immunoassay for Diagnosis and Follow‐up of ANCA‐Associated Vasculitis and Goodpasture's Disease

We have evaluated a new-multiplex immunoassay (FIDIS Vasculitis) for simultaneous detection and quantification of anti-MPO, -PR3, and -glomerular basement membrane (GBM) antibodies in diagnosis and follow-up of ANCA-associated vasculitides (AAV) and Goodpasture's disease. ANCA were determined in sera of (a) 87 consecutive patients with biopsy-proven pauci-immune NCGN and 72 controls; (b) 9 patients with Goodpasture's disease; and (c) 60 WG patients and 60 controls, previously used in a multicenter comparison of direct and capture ELISA for PR3-ANCA. Finally, for prediction of relapses, PR3-ANCA was measured in samples preceding relapse in 23 PR3-AAV patients and in 23 matched PR3-AAV patients without relapse. The relative sensitivity of the FIDIS Vasculitis assay was 97.4% for MPO-ANCA and 92.3% for PR3-ANCA; specificity was 100% and 97.2%, respectively. Evaluation of the anti-GBM antibody detection revealed a sensitivity of 100% and a specificity of 99.6%. The sensitivity for WG of the PR3-ANCA detection (71.6%) approached the performance of capture ELISA (74%), although at the cost of specificity (96.7% versus 100%). For prediction of relapses a rise of 50% in ANCA level by FIDIS Vasculitis appeared optimal (ROC curve) for prediction of relapses. However, as compared to capture ELISA, both positive (63% versus 76%) and negative (68% versus 72%) predictive values were reduced. In conclusion, simultaneous detection of anti-MPO, -PR3, and -GBM antibodies in the multiplex FIDIS Vasculitis assay has excellent performance in terms of diagnosis of patients with AAV or Goodpasture's disease. However, detection of rises in PR3-ANCA for prediction of relapses gives less optimal results when compared to capture ELISA.

ANCA-GBM dot-blot: evaluation of an assay in the differential diagnosis of patients presenting with rapidly progressive glomerulonephritis.

Rapidly progressive glomerulonephritis (RPGN) is characterized by rapid and progressive loss of renal function and the presence of crescentic glomerulonephritis (CGN). Early diagnosis and appropriate treatment is mandatory to prevent death and/or renal failure. We have evaluated an ANCA-GBM dot-blot diagnostic test in terms of sensitivity, specificity, and inter-observer effect in consecutive patients with RPGN ( n = 82). Control sera ( n = 34) included healthy and relevant disease controls. Dot-blots were independently evaluated by nine observers. Proteinase 3 (PR3)-ANCA, myeloperoxidase (MPO)-ANCA, and both were detected by ELISA in 36, 32, and 3 samples of 71 patients with pauci-immune CGN, respectively. Two additional samples were ANCA negative. The dot-blot revealed a sensitivity of 92-95% for PR3-ANCA and 80-86% for MPO-ANCA. The specificity of the dot-blot for PR3- and MPO-ANCA was 100%. In the patients with anti-GBM nephritis ( n = 9) anti-GBM was detected by both ELISA and dot-blot (sensitivity: 100%). The specificity of the anti-GBM dot-blot was 91-94%. However, the inter-observer effect was relatively high for detection of anti-GBM antibodies (24%). In conclusion, the ANCA-GBM dot-blot is a useful screening tool in situations where conventional ANCA testing is not readily available with excellent performance for PR3-ANCA detection, but less optimal sensitivity for MPO-ANCA and specificity for anti-GBM detection. Therefore, it is recommended to include the following advises in the report to the physicians: 1) patients with a high clinical suspicion for MPO-ANCA-associated RPGN and negative dot-blot must have conventional analysis for MPO-ANCA, and 2) negative anti-GBM dot-blot makes anti-GBM disease very unlikely, but positive samples should be confirmed by conventional anti-GBM tests.

Goodpasture's disease in the absence of circulating anti-glomerular basement membrane antibodies as detected by standard techniques

Goodpasture's disease is characterized by rapidly progressive glomerulonephritis, often accompanied by pulmonary hemorrhage, in association with deposition of antibodies in a linear pattern on the glomerular basement membrane (GBM). The diagnosis of Goodpasture's disease in patients with acute renal failure often relies on the use of immunoassays to detect circulating anti-GBM antibodies in serum samples. We describe three cases of Goodpasture's disease in which no circulating anti-GBM antibodies were detectable in serum by well-established enzyme-linked immunosorbent assay or Western blotting techniques. The diagnosis of Goodpasture's disease was confirmed by renal biopsy, with linear deposition of immunoglobulin along the GBM and crescentic glomerulonephritis. In addition, an alternative method of antibody detection using a highly sensitive biosensor system confirmed that circulating antibodies were present in sera from both patients tested. Because this technique is not routinely available for the detection of anti-GBM antibodies, we suggest that diagnosis always be confirmed with a renal biopsy, and despite negative serological test results using immunoassay, the diagnosis of Goodpasture's disease should still be considered in the correct clinical context. © 2002 by the National Kidney Foundation, Inc.