Testing and reporting antineutrophil cytoplasmic antibodies (ANCA) in treated vasculitis and non-vasculitic disease

The Role of Neutrophils in ANCA-Associated Vasculitis: The Pathogenic Role and Diagnostic Utility of Autoantibodies

Recent years have brought progress in understanding the role of the neutrophil, dispelling the dogma of homogeneous cells mainly involved in the prime defence against pathogens, shedding light on their pathogenic role in inflammatory diseases and on the importance of antineutrophil-cytoplasmic antibodies' pathogenic role in ANCA-associated vasculitides vasculitis (AAV). Myeloperoxidase (MPO) and proteinase 3 (PR3) expressed in neutrophil granulocytes are the most common targets for ANCAs and contribute to the formation of MPO-ANCAs and PR3-ANCAs which, released to the bloodstream, become an excellent diagnostic tool for AAV. In this study, we focus on increasing the clinical and experimental evidence that supports the pathogenic role of ANCAs in AAV. Additionally, we discuss the diagnostic utility of ANCAs for disease activity and prognosis in AAV. Understanding the central role of ANCAs in AAV is crucial for advancing our knowledge of these complex disorders and developing targeted therapeutic strategies in the era of personalized medicine.

Improvement of indirect immunofluorescence technique to detect antineutrophil cytoplasmic antibodies and its impact on test positivity rate

The indirect immunofluorescence (IIF) technique for antineutrophil cytoplasmic antibodies (ANCA) detection is subject to substantial differences across laboratories. This study aimed to assess the impact of improvements in the IIF-ANCA technique on the positivity rate of ANCA tests. A cross-sectional study was performed with serum samples from patients with ANCA-associated vasculitis (AAV), autoimmune hepatitis (AIH), and ulcerative colitis (UC). A paired analysis was performed for IIF-ANCA results using the traditional method and a modified protocol after a series of specific adjustments in the technique based on the protocol of IIF-ANCA test performed at a nation-wide private laboratory in Brazil. ANCA specificity was assessed by ELISA for anti-proteinase 3 (PR3) and anti-myeloperoxidase (MPO) antibodies. Sixty-one patients were evaluated. The positivity rate of IIF-ANCA tests at disease presentation performed at the University reference laboratory was 32.3% in AAV, AIH, and UC patients, whereas the positivity rates of IIF-ANCA and ELISA tests in other laboratories were 75.0 and 72.7%, respectively. After modifications in the IIF-ANCA technique, there was a significant increase in the positivity rate (14.8 vs 34.3%; P=0.0002) and in median titers [1/40 (1/30-1/160) vs 1/80 (1/40-1/80); P=0.0003] in AAV, AIH, and UC patients. UC had the highest increment in positive results from 5.3 to 36.8%. There was poor agreement between MPO- or PR3-ANCA and both IIF-ANCA techniques. In conclusion, modifications in the IIF-ANCA protocol led to a significant improvement in its positivity rate and titers.

Case report: A pediatric case of MPO-ANCA-associated granulomatosis with polyangiitis superimposed on post-streptococcal acute glomerulonephritis

An eight-year-old girl was admitted with vomiting, gross hematuria, and progressive renal dysfunction. A renal biopsy revealed endocapillary proliferative glomerulopathy and crescent formation. Immunofluorescence staining revealed diffuse granular deposits of IgG and C3. Post-streptococcal acute glomerulonephritis (PSAGN) was suspected, based on the elevated anti-streptolysin O levels, decreased serum C3 concentrations, and histologic findings. The myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) test was positive, and the young patient gradually developed palisaded neutrophilic and granulomatous dermatitis (PNGD), orbital and paranasal sinus granulomatous neoplasms, along with intermittent nose, head, and orbital pain. Finally, she was diagnosed with the rare MPO-ANCA-associated granulomatosis with polyangiitis (GPA) superimposed on PSAGN. The patient was treated with aggressive renal replacement therapy, methylprednisolone pulse therapy, and intravenous pulse cyclophosphamide; her renal function normalized, and her pain symptoms improved.

Interference of Antinuclear Antibody (ANA) in Indirect Immunofluorescence Assay (IIFA)-Based Perinuclear Antineutrophil Cytoplasmic Antibody (pANCA) Interpretation

Background

Indirect immunofluorescence assay (IIFA) based on antineutrophil cytoplasmic antibody (ANCA) testing is a commonly employed test for diagnosing autoimmune vasculitis. Antinuclear antibody (ANA) can give rise to a false interpretation of perinuclear-ANCA (pANCA) in ethanol-fixed granulocyte substrates. Analytical interference could frequently occur in setups where ethanol-fixed substrates are used alone. Here, we intend to investigate this ANA interference in pANCA interpretation.

Methods

In this retrospective study, we studied anti-MPO-negative but ANA-positive and pANCA (IIFA based) samples. We also correlated immunoblot results (where data were available) and checked the association between grades of blot positivity (an indicator of the concentration of ANA) and frequency of pANCA interpretation. Data were analyzed by appropriate statistical techniques (Chi-square and kappa statistics).

Results

About 19.2% of ANA blot (ENA-blot) positive samples displayed a pANCA positive pattern in the ethanol-fixed substrate, while this positivity in ENA-blot negatives was 6.5%. In positive ANA-IIFA samples, about 14.7% yielded pANCA patterns (on ethanol fixed substrates). Out of this, nuclear homogenous pattern yielding samples gave the highest frequency pANCA, that is, in 31.5% followed by speckled (11.1%), DFS (10.3%), and centromere (6.7%).The association of the nuclear homogenous pattern was statistically significant.

Conclusions

ANA-positive results may interfere with the interpretation of pANCA as observed in ANA-IIFA and ENA-blot positive samples. ANA-IIFA patterns like nuclear homogenous may strongly associate this pANCA interpretation. This can help laboratories perform ANCA testing more effectively, ruling out ANA interference in ANCA screening.

Glomerular IgA Deposition and Serum Antineutrophil Cytoplasmic Antibody Positivity in a Child With Dystrophic Epidermolysis Bullosa: Case Report and Literature Review

Patients with epidermolysis bullosa (EB) could develop significant urological complications, such as hydroureteronephrosis, renal amyloidosis and IgA nephropathy (IgAN). Here, we presented a 12-year-old boy carrying pathogenic COL7A1 mutation with diagnosis of dystrophic epidermolysis bullosa (DEB). The patient had concomitant gross hematuria and proteinuria. Pathological examinations and immunostaining of renal biopsy showed glomeruli with mesangial hypercellularity and deposition of IgA, which were indicative of IgAN. Interestingly, serological evaluation showed antineutrophil cytoplasmic antibody (ANCA) directed against myeloperoxidase and proteinase 3. Treatment with glucocorticoid, immunosuppressants, angiotensin-converting enzyme inhibitor and antibiotics efficiently improved hemato-proteinuria, and ANCAs became negative as well. This case of DEB presented a unique collection of clinical manifestations and pathological alterations. IgAN and serum positive ANCA were possibly associated with sustained infection secondary to DEB, and can be managed by empirical treatment for primary IgAN.

Management of Severe Oral Inflammatory Conditions in Dogs and Cats

Severe oral inflammatory disease is not uncommon in the mouths of canine and feline patients. An approach to oral diagnosis is offered. This article discusses a brief review of important points in the oral diagnosis and management of main canine (canine chronic ulcerative stomatitis (CCUS), eosinophilic stomatitis, and Wegener's granulomatosis (WG)) and feline diseases (feline gingivostomatitis/caudal stomatitis, oral eosinophilic lesions, pyogenic granuloma, and autoimmune diseases with oral manifestations), and-whereby possible-information about the current understanding of disease pathogenesis and treatment is offered.

Antineutrophil cytoplasmic antibodies (ANCA) - their role in pathogenesis, diagnosis, and treatment monitoring of ANCA-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) constitutes a group of rare diseases characterized by necrotizing inflammation of small blood vessels and the presence of ANCA. Increasing clinical and experimental evidences support their pathogenic role in AAV, but the exact mechanism is not fully understood. Recently, the important role of neutrophil extracellular traps (NETs) in pathogenesis of AAV is underlined. There is an indication that NETs can be a source for the formation of ANCA. The most common ANCA target antigens are myeloperoxidase (MPO) and proteinase 3 (PR3). Though the mechanism of action of ANCA is still under exploration, ANCA serology is being increasingly used for classification of AAV and revealed as kenner in defining various disease subsets associated with different genetic background, clinical features, treatment response, and prognosis. Controversy exists regarding the utility of serial measurements of ANCA in patients with AAV to monitor treatment and predict disease relapse.

The value of anti-neutrophil cytoplasmic antibodies (ANCA) testing for the diagnosis of ANCA-associated vasculitis, a systematic review and meta-analysis

The testing of anti-neutrophil cytoplasmic antibodies (ANCA) takes an important place in the diagnostic workup to ANCA-associated vasculitis (AAV). Nowadays, it is recommended to screen for the presence of PR3 and MPO specific antibodies first using immunoassay, without the need for ANCA measurement by indirect immunofluorescence (IIF). A literature search was performed to assess the diagnostic test value of ANCA IIF and PR3- and MPO-antibody immunoassay to diagnose AAV. This meta-analysis shows that the c-ANCA testing by IIF has a pooled sensitivity of 75.2% and a pooled specificity of 98.4%. For PR3-antibody immunoassay, the pooled sensitivity depended on the immunoassay method used, and ranged from 79.8% to 86.6%, whereas the pooled specificity ranged from 96.8% to 98.3%. For both p-ANCA IIF and MPO-antibody immunoassay (all methods) sensitivity varied considerably showing pooled values of respectively 46.3% and 58.1%, whereas respective pooled specificity was 91.4% and 95.6%. These findings support the 2017 international consensus that primary anti-PR3 and anti-MPO screening by immunoassay, based on superior immunoassay sensitivity without the need for IIF ANCA testing, improves the diagnostic workup of AAV.

2020 international consensus on ANCA testing beyond systemic vasculitis

This document follows up on a 2017 revised international consensus on anti-neutrophil cytoplasm antibodies (ANCA) testing in granulomatosis with polyangiitis and microscopic polyangiitis and focuses on the clinical and diagnostic value of ANCA detection in patients with connective tissue diseases, idiopathic interstitial pneumonia, autoimmune liver diseases, inflammatory bowel diseases, anti-glomerular basement membrane (GBM) disease, infections, malignancy, and during drug treatment. Current evidence suggests that in certain settings beyond systemic vasculitis, ANCA may have clinical, pathogenic and/or diagnostic relevance. Antigen-specific ANCA targeting proteinase-3 and myeloperoxidase should be tested by solid phase immunoassays in any patient with clinical features suggesting ANCA-associated vasculitis and in all patients with anti-GBM disease, idiopathic interstitial pneumonia, and infective endocarditis associated with nephritis, whereas in patients with other aforementioned disorders routine ANCA testing is not recommended. Among patients with autoimmune liver diseases or inflammatory bowel diseases, ANCA testing may be justified in patients with suspected autoimmune hepatitis type 1 who do not have conventional autoantibodies or in case of diagnostic uncertainty to discriminate ulcerative colitis from Crohn's disease. In these cases, ANCA should be tested by indirect immunofluorescence as the target antigens are not yet well characterized. Many questions concerning the optimal use of ANCA testing in patients without ANCA-associated vasculitis remain to be answered.

Drug-induced cutaneous vasculitis and anticoagulant-related cutaneous adverse reactions: insights in pathogenesis, clinical presentation, and treatment

Drug-induced vasculitis and anticoagulant-related skin reactions are commonly encountered in the inpatient and outpatient settings. The spectrum of clinical presentation is broad and ranges from focal, skin-limited disease, to more extensive cutaneous and soft tissue necrosis, to potentially fatal systemic involvement. The prompt recognition of these adverse events can have a significant impact on patient morbidity and mortality. We highlight the key features of the clinical presentation with an emphasis on primary lesion morphology, distribution, and epidemiology of purpuric drug reactions. The proposed pathophysiology, histologic findings, and therapeutic interventions of these potentially life-threatening diseases are discussed.

Coughing up clues: 16-year-old girl with acute haemoptysis

A 16-year-old previously well girl presented with bilateral painful lower leg swelling and non-pruritic blanching rash across her torso and upper and lower limbs. These symptoms started after commencing amoxicillin for presumed tonsillitis. She was diagnosed with serum sickness-like illness and started on non-steroidal agents. The rash and painful leg swelling improved over the next 48 hours. However, she subsequently developed fevers, cough and new-onset haemoptysis.She continued to deteriorate with increasing amounts of haemoptysis, work of breathing and escalating respiratory support requirements. Serial chest radiographs showed worsening lung consolidation and enlarging pleural effusion. A CT chest revealed extensive bilateral lung consolidation, most likely pulmonary haemorrhage. Subsequent investigations showed positive classic antineutrophil cytoplasmic antibody, confirming the diagnosis of granulomatosis with polyangiitis.