Negative Indirect Immunofluorescence Research Articles

065 Evaluating pathogenicity of skin autoantibodies in hereditary epidermolysis bullosa hints towards predisposition of autoimmunity

Skin blistering disorders result from damaged proteins involved in the dermal-epidermal adhesion. The damage is either caused by genetically induced defects or by autoantibodies targeting those proteins. In hereditary epidermolysis bullosa (EB) skin blistering is pathogenetically linked to genetic deficiency of distinct proteins of the epidermis or the dermal-epidermal junction, but circulating autoantibodies against these proteins have also been identified in EB patients. So far, the pathogenetic role of these autoantibodies is unclear, as they do not bind the respective skin structures, as shown by negative indirect immunofluorescence (IIF).

Serration pattern analysis as a practical adjunct tool for categorization of subepidermal autoimmune blistering diseases.

Serration pattern analysis helps in the classification of subepidermal autoimmune blistering disorders; more precisely, it helps to differentiate epidermolysis bullosa acquisita from other subepidermal autoimmune blistering disorders. Most of the published reports of this tool have come from a single center. The objectives of the study were to study the utility of serration pattern analysis in classifying subepidermal autoimmune blistering disorders. Seventy five cases of subepidermal autoimmune blistering disorders were enrolled in this prospective study. A three millimeter punch biopsy was taken from the perilesional skin or mucosa for direct immunofluorescence; indirect immunofluorescence was carried out using salt-split skin. Subclassification of subepidermal autoimmune blistering disorders was done based on direct immunofluorescence, indirect immunofluorescence on salt-split skin, indirect immunofluorescence using knockout skin and serration pattern analysis findings. Indirect immunofluorescence was positive in 68 cases; 14 cases showed a dermal staining pattern while the rest showed either an epidermal or a combined pattern. All patients with epidermal or combined staining patterns showed "n" serrated pattern on direct immunofluorescence. Nine patients with dermal staining on indirect immunofluorescence also revealed an "n" serration pattern on direct immunofluorescence indicating the diagnosis of anti-p200 pemphigoid, and the rest showed a "u" serrated pattern. Three patients with negative indirect immunofluorescence showed "u" serration on direct immunofluorescence while the rest showed "n" serration. ELISA and immunoblotting could not be performed due to resource constraints. Based on indirect immunofluorescence and serration pattern analysis, classification of the majority of patients with subepidermal autoimmune blistering disorders was possible in our study. Pattern recognition is a cost-effective tool and can be easily learnt. It is recommended to be practiced in all laboratories where facilities for advanced immunological diagnosis are unavailable.

Internal audit of two antineuronal immunoblots and the role of indirect immunofluorescence in sample screening

Anti-neuronal antibodies are associated with a range of clinical phenotypes that are often preceded by malignancy. Most of these antibodies can be identified by indirect immunofluorescence (IIF) using commercial primate neural tissue slides. The EUROImmun 12 and upgraded RAVO 14 antigen line immunoblots were directly compared to replace a 9 antigen RAVO immunoblot. Initial assessment was with samples with known positive specificities by IIF. The second phase involved parallel testing of routine pooled negative IIF samples as per institutional standard antineuronal testing algorithm. IIF results and clinical correlation were used to arbitrate on discordant immunoblot results. Correlation in known positives was 80%. The EUROImmun immunoblot did not identify disease causing SOX1 and Recoverin antibodies. Routine pooled analysis did not identify discrepancy between the platforms. Assessment of 318 patient samples did not reveal any cases where a diagnosis was correctly identified by line immunoblot and not IIF. A single sample with positive Yo antibodies was identified by both platforms without clinical or IIF correlation, making this a likely false positive. Subsequent to this audit, Westmead ICPMR has migrated to the 14 antigen RAVO line blot for confirmation of positive IIF or for patients with equivocal results only.

Autoantibody profile in eosinophilic granulomatosis and polyangiitis: predominance of anti-alpha-enolase antibodies.

To evaluate the autoantibody profile in eosinophilic granulomatosis and polyangiitis (EGPA) patients. 33 EGPA patients were tested for anti-neutrophil cytoplasmic antibodies (ANCA), antinuclear antibodies (ANA), rheumatoid factor (RF), anti-alpha-enolase antibodies, and anti-eosinophil peroxidase (EPO) antibodies. Granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), hypereosinophilic syndrome (HES), rheumatoid arthritis (RA), primary biliary cirrhosis (PBC) patients and healthy subjects were tested as a control group. Anti-alpha-enolase antibodies were positive in 82% of EGPA patients at high titers. Although a high sensitivity was shown for an anti-alpha-enolase antibody titer above 1/100 (82%), the specificity for EGPA remained low (44%) (AUC=0.653, p=0.008). Anti-alpha-enolase antibodies predominated in males with EGPA (p=0.048) and were associated with skin involvement (p=0.040). Most of the EGPA patients positive for anti-alpha enolase antibodies (20 out of 27) had a negative indirect immunofluorescence test (IFT) for ANCA. ANCA were positive in 8 EGPA patients (24%) with a perinuclear pattern in all but one patient. The ANCA-target antigen was myeloperoxidase (MPO) and/or alpha-enolase. A usually fine-speckled ANA pattern was observed in 42% of the EGPA patients. RF was positive in 1 (6%) of the 18 EGPA patients tested. There was no association between the presence and levels of autoantibodies and EGPA disease activity. None of the patients and controls was positive for anti-EPO antibodies. Alpha-enolase may be a target of autoimmunity in EGPA patients and shows usually negative ANCA IFT results.

The clinical relevance of anti-dsDNA antibodies determined by the Elia™ dsDNA assay in patients with negative indirect immunofluorescence on the HEp-2cell.

Data on the clinical importance of the detection of anti-dsDNA antibodies in patients with negative indirect immunofluorescence on the HEp-2cell (IIF) are sparse and are especially not available for all common commercially available assays. This study aimed to assess the clinical significance of anti-dsDNA antibodies determined by the Elia™ dsDNA assay in patients with negative IIF. We retrospectively examined the medical records of 234 consecutive subjects with detectable anti-dsDNA antibodies determined by the Elia™ dsDNA assay. A total of 124 subjects with detectable anti-dsDNA autoantibodies were IIF-negative, but yielded positive or borderline results in the Elia™ CTD screen assay for antinuclear antibodies (ANA). Within this group, 6/49 IIF-negative patients (12%) with ANA-associated systemic autoimmune rheumatic disorders (AASARD) and 118/185 subjects (64%) with various other diseases (Non-AASARD) were identified. There was no statistically significant difference with regard to the concentrations of anti-dsDNA antibodies (p=0.53) between the AASARD and the Non-AASARD group. Within the AASARD group, four patients diagnosed with systemic lupus erythematosus (SLE, treated), discoid lupus erythematosus (untreated), indetermined connective tissue disease (untreated) and polymyositis (treated) had positive anti-dsDNA autoantibodies, whereas two patients with treated SLE, thereby one in remission, had borderline concentrations of anti-dsDNA antibodies. Our findings suggest that the detection of anti-dsDNA antibodies in IIF-negative patients can be of clinical relevance in some cases. Our results further support the combined use of IIF and solid-phase assays in screening algorithms for ANA, in order to avoid overlooking potentially important autoantibody entities.

A hierarchical bivariate meta-analysis of diagnostic test accuracy to provide direct comparisons of immunoassays vs. indirect immunofluorescence for initial screening of connective tissue diseases.

To compare indirect immunofluorescence (IIF) for antinuclear antibodies (ANA) against immunoassays (IAs) as an initial screening test for connective tissue diseases (CTDs). A systematic literature review identified cross-sectional or case-control studies reporting test accuracy data for IIF and enzyme-linked immunosorbent assays (ELISA), fluorescence enzyme immunoassay (FEIA), chemiluminescent immunoassay (CLIA) or multiplex immunoassay (MIA). The meta-analysis used hierarchical, bivariate, mixed-effect models with random-effects by test. Direct comparisons of IIF with ELISA showed that both tests had good sensitivity (five studies, 2321 patients: ELISA: 90.3% [95% confidence interval (CI): 80.5%, 95.5%] vs. IIF at a cut-off of 1:80: 86.8% [95% CI: 81.8%, 90.6%]; p = 0.4) but low specificity, with considerable variance across assays (ELISA: 56.9% [95% CI: 40.9%, 71.5%] vs. IIF 1:80: 68.0% [95% CI: 39.5%, 87.4%]; p = 0.5). FEIA sensitivity was lower than IIF sensitivity (1:80: p = 0.005; 1:160: p = 0.051); however, FEIA specificity was higher (seven studies, n = 12,311, FEIA 93.6% [95% CI: 89.9%, 96.0%] vs. IIF 1:80 72.4% [95% CI: 62.2%, 80.7%]; p < 0.001; seven studies, n = 3251, FEIA 93.5% [95% CI: 91.1%, 95.3%] vs. IIF 1:160 81.1% [95% CI: 73.4%, 86.9%]; p < 0.0001). CLIA sensitivity was similar to IIF (1:80) with higher specificity (four studies, n = 1981: sensitivity 85.9% [95% CI: 64.7%, 95.3%]; p = 0.86; specificity 86.1% [95% CI: 78.3%, 91.4%]). More data are needed to make firm inferences for CLIA vs. IIF given the wide prediction region. There were too few studies for the meta-analysis of MIA vs. IIF (MIA sensitivity range 73.7%-86%; specificity 53%-91%). FEIA and CLIA have good specificity compared to IIF. A positive FEIA or CLIA test is useful to support the diagnosis of a CTD. A negative IIF test is useful to exclude a CTD.

A High Anti-Desmoglein 3 Antibody ELISA Index and Negative Indirect Immunofluorescence in Two Patients in Remission with Pemphigus Vulgaris

A High Anti-Desmoglein 3 Antibody ELISA Index and Negative Indirect Immunofluorescence in Two Patients in Remission with Pemphigus Vulgaris

Aquaporin 4 IgG Serostatus and Outcome in Recurrent Longitudinally Extensive Transverse Myelitis

Studies focused on recurrent longitudinally extensive transverse myelitis (rLETM) are lacking. To determine the aquaporin 4 (AQP4) IgG detection rate using recombinant human APQ4-based assays in sequential serum specimens collected from patients with rLETM categorized as negative by first-generation tissue-based indirect immunofluorescence (IIF) assay and to define the clinical characteristics and motor disability outcomes in AQP4-IgG-positive rLETM. A search of the Mayo Clinic computerized central diagnostic index (October 1, 2005, through November 30, 2011), cross-linked with the Neuroimmunology Laboratory database, identified 48 patients with rLETM, of whom 36 (75%) were positive and 12 (25%) negative for neuromyelitis optica (NMO) IgG (per IIF of serial serum specimens). Stored serum specimens from "seronegative" patients were retested with recombinant human AQP4-based assays, including enzyme-linked immunosorbent, transfected cell-based, and fluorescence-activated cell-sorting assays. Control patients included 140 AQP4-IgG-positive patients with NMO, of whom a subgroup of 20 initially presented with 2 attacks of transverse myelitis (rLETM-onset NMO). AQP4-IgG serostatus, clinical characteristics, and Expanded Disability Status Scale score. Six patients with negative IIF results were reclassified as AQP4-IgG positive, yielding an overall AQP4-IgG seropositivity rate of 89%. Fluorescence-activated cell-sorting, cell-based, and enzyme-linked immunosorbent assays improved the detection rate to 89%, 85%, and 81%, respectively. The female to male ratio was 2:3 for AQP4-IgG-negative rLETM and 5:1 for AQP4-IgG-positive patients. The AQP4-IgG-positive patients with rLETM or rLETM-onset NMO were similar in age at onset, sex ratio, attack severity, relapse rate, and motor disability. From Kaplan-Meier analyses, 36% of AQP4-IgG-positive patients with rLETM are anticipated to need a cane to walk within 5 years after onset. For patients with rLETM-onset NMO, the median time from onset to first optic neuritis attack (54 months) was similar to the median disease duration for AQP4-IgG-positive patients with rLETM (59 months). The median number of attacks was 3 for AQP4-IgG-positive patients with rLETM (range, 2-22), and the first optic neuritis attack for those with rLETM-onset NMO followed a median of 3 myelitis attacks (range, 2-19). Immunosuppressant therapy reduced the relapse rate in both AQP4-IgG-positive and AQP4-IgG-negative patients with rLETM. Recombinant antigen-based assays significantly increase AQP4-IgG detection in patients with rLETM, and AQP4-IgG-negative adults with rLETM are rare. Evolution to NMO can be anticipated in AQP4-IgG-positive patients. Early initiation of immunotherapy may result in a more favorable motor outcome.

Spectrum of ANCA-Associated Disorders According to Serological Phenotype in Routine Care: Retrospective Case Series of 209 Patients

Objective : To summarize the experience of three years of positive ANCA (anti-neutrophil cytoplasmic antibodies) testing in a single university based hospital. We describe the clinical features according to ANCA phenotype of patients who did and did not have ANCA- associated vasculitis (AAV). Methods : We did a review of all samples tested for ANCA in a 3 year-period (2005-2007). Each sample was tested by indirect immunofluorescence (IIF) and enzyme-linked-immunosorbent assay (ELISA). Sera were considered as positive for ANCA testing if either IIF or ELISA for MPO or PR3 antigen specificity was positive. Patients were considered as having AAV on established diagnostic criteria and algorithms. Results : The positive ANCA population consisted in 209 patients, 54 were classified in the AAV group and 155 patients constituted the “Others” group. The typically most relevant ANCA phenotypes (C-ANCA/anti-PR3+ and P-ANCA/anti-MPO+) were detected in 90 % (49/54) of patients in the AAV group and only 10% (15/155) of the “Others” group (p < 0.001). Among the latter none developed AAV during follow-up. Positive IIF alone was found in 4% (2/54) of the AAV group and in 68% (105/155) of the “Others” group (p < 0.001). In patients without AAV, positive IIF alone or positive ELISA with negative IIF represented the main ANCA pattern. Conclusion : In routine clinical practice, most patients with positive ANCA testing do not have AAV. The typical ANCA pattern (C-ANCA/anti-PR3+ or P-ANCA/anti-MPO+) remains a strong predictor of AAV in patients with a high level of suspicion for systemic vasculitis. In other cases, ANCA positivity should be interpreted with extreme caution.

Correlation of antibodies against desmogleins 1 and 3 with indirect immunofluorescence and disease status in a Greek population with pemphigus vulgaris

The use of ELISA testing of antibodies to desmogleins 1 and 3 (anti-Dsg1 and anti-Dsg3) and indirect immunofluorescence (IIF) has been strongly supported for the serologic diagnosis of pemphigus. The purpose of this study was to correlate anti-Dsg1 and anti-Dsg3 with IIF values, disease localization, treatment and clinical course in Greek patients with pemphigus vulgaris (PV). A total of 54 patients with PV had ELISA serum testing for the presence and titers of anti-Dsg1, anti-Dsg3 and IIF. Anti-Dsg1, anti-Dsg3 and IIF were correlated with treatment and disease localization. For 40 patients, titers of anti-Dsg1 and anti-Dsg3 were assessed in relation to treatment and clinical course after 12 months. Anti-Dsg3 and anti-Dsg1 positivity in patients with negative IIF was 70.6% and 58.8%, respectively. Anti-Dsg1 and anti-Dsg3 were positive in 89.3% and 100% of patients with mucocutaneous disease, respectively, 88.9% and 66.7% of patients with skin limited disease, respectively and 52.9% and 76.5% of patients with mucosal limited disease, respectively. Both antibody titers showed significant correlation with IIF and treatment status. Improvement of clinical status was associated with significant decrease of both anti-Dsg1 and anti-Dsg3 after 12 months. Serum testing of anti-Dsg1 and anti-Dsg3 in PV patients not only provides significant correlations with IIF, treatment and disease type, but may serve as a monitoring tool for clinical course and treatment guidance.

Dermatitis Herpetiformis Sera or Goat Anti–Transglutaminase-3 Transferred to Human Skin-Grafted Mice Mimics Dermatitis Herpetiformis Immunopathology

Dermatitis herpetiformis (DH) is characterized by deposition of IgA in the papillary dermis. However, indirect immunofluorescence is routinely negative, raising the question of the mechanism of formation of these immune deposits. Sárdy et al. (2002. J. Exp. Med. 195: 747-757) reported that transglutaminase-3 (TG3) colocalizes with the IgA. We sought to create such deposits using passive transfer of Ab to SCID mice bearing human skin grafts. IgG fraction of goat anti-TG3 or control IgG were administered i.p. to 20 mice. Separately, sera from seven DH patients and seven controls were injected intradermally. Biopsies were removed and processed for routine histology as well as direct immunofluorescence. All mice that received goat anti-TG3 produced papillary dermal immune deposits, and these deposits reacted with both rabbit anti-TG3 and DH patient sera. Three DH sera high in IgA anti-TG3 also produced deposits of granular IgA and TG3. We hypothesize that the IgA class anti-TG3 Abs are directly responsible for the immune deposits and that the TG3 is from human epidermis, as this is its only source in our model. These deposits seem to form over weeks in a process similar to an Ouchterlony immunodiffusion precipitate. This process of deposition explains the negative indirect immunofluorescence results with DH serum.

Update on anti-NMO IgG antibodies

Neuromyelitis optica (NMO) or Devic’s syndrome is a severe idiopathic and relapsing, demyelinating disease characterised by optic neuritis (ON) and longitudinally extensive transverse myelitis (LETM). 1 Neuropathologically, NMO is characterised by extensive demyelination with partial necrosis of the spinal cord white and grey matter, acute axonal injury, neutrophil and eosinophil infiltrates, IgG and IgM deposition and perivascular complement activation. NMO is distinguished from classical multiple sclerosis (MS) by clinical, neuroimaging, CSF and serological criteria. 1 The identification of NMO-IgG by indirect immunofluorescence (IIF) was initially described as a highly specific marker with the titre paralleling the disease activity. However, the sensitivity of IIF is variable (58–75%) for clinical NMO. Consequently, numerous methods using aquaporin 4 (AQP4) as the target antigen have been developed in an attempt to improve sensitivity. Apart from cell-based assays, these have failed to improve on the sensitivity of IIF. Recently, it has been demonstrated that NMO-IgG targets mainly the M-23 isoform of AQP4 that structurally organises itself into orthogonol arrays of particles in cell membranes. As AQP4-Ab recognises conformational epitopes, the lower sensitivity of all but the cell-based assays may be due to changes resulting during purification, fixation or other causes of NMO, i.e., parainfectious NMO. As indirect immunofluorescence is the most widely available method for detecting NMO-IgG, the Pathology Queensland experience has raised issues of the ‘true’ sensitivity of NMO-IgG testing for NMO as well as identifying other autoantibodies (including anti-reticulin and anti-nuclear antibodies) that cause interference and make IIF interpretation difficult. These issues may contribute to both false positive and false negative IIF results. Some authors have suggested 2 that the published sensitivities of NMO-IgG may be artificially high and this has prompted the proposed Australian and New Zealand NMO study designed to evaluate the sensitivity and specificity of all currently available methods for NMO-IgG.

Anti-Leishmania titers and positive skin tests in patients cured of kala-azar

Visceral leishmaniasis (VL), also known as kala-azar, is an important public health problem. If not treated, virtually all clinically symptomatic patients die within months. The diagnosis is based on the Montenegro skin test (MST) and anti-Leishmania titers. Nevertheless, the time required for cured individuals living in a leishmaniasis-endemic area to present a positive skin test and negative anti-Leishmania serology is known. To determine the cellular and humoral immune response profile in relation to different times post-VL cure, a cross-sectional study was conducted on subjects from a kala-azar endemic area in Paço do Lumiar, MA, Brazil, on the basis of 1995-2005 notifications reported by the National Health Foundation/Regional Coordination of Maranhão. We visited cured individuals with a history of VL within the last 10 years. Seventy-four subjects (30 females) ranging in age from 1 to 44 years were included, all of them symptom free at the time of the study. A cellular immune response was observed in 73 (98.6%) subjects, whereas no significant antibody titers were detected by indirect immunofluorescence (IIF) in the sera of 69 (93.2%) cases. Ten years post-cure, 39 (52%) subjects had a positive MST and negative IIF reaction, while in one subject the skin and anti-Leishmania serology tests were negative. Two other subjects were positive in both tests 1 year after cure. These data suggest that a cellular immune response may still be present in subjects cured of VL regardless of post-cure time, and that the parasite persists in the host after clinical cure of the disease. This would explain the persistence of significant Leishmania sp antibody titers in some subjects after treatment.

Junctional adhesion molecule overexpression in Kaposi varicelliform eruption skin lesions - as a possible herpes virus entry site

Context:Herpes simplex virus (HSV) infection of the skin represents a common challenge in dermatology; however, currently the port of viral entry remains obscure. HSV is known to induce an immunoglobulin-binding cell surface receptor in infected cells that utilizes a non-immune mechanism. The replication of HSV in cultured cells is accompanied by the appearance of surface receptors with an affinity for the Fc region of immunoglobulin G.Case Report:We describe a 43 year old African American male who presented with a generalized rash, including intense pruritus and umbilicated vesiculopustules. The patient had been previously diagnosed and treated for psoriasis with methotrexate and prednisone. Hematoxylin and eosin demonstrated keratinocytes with ballooning degeneration within the epidermis. Direct immunofluorescence (DIF) results resembled the pattern of paraneoplastic pemphigus, with negative indirect immunofluorescence (IIF) results on rat bladder. Immunohistochemistry revealed deposits of the complement membrane attack complex within dermal sweat glands, as well as the presence of herpes simplex virus 1 on the skin. We report a case of Kaposi varicelliform eruption, a cutaneous eruption caused by a virus infecting patients with pre-existing dermatoses.Conclusion:HSV virus infection with over-expression of the junctional adhesion molecule close to herpetic infection sites may preferentially increase viral entry through the skin, possibly triggering a Kaposi varicelliform eruption.

Comparison of desmoglein ELISA and indirect immunofluorescence using two substrates (monkey oesophagus and normal human skin) in the diagnosis of pemphigus

A prospective study was performed to assess the usefulness of desmoglein enzyme-linked immunosorbent assay testing compared with indirect immunofluorescence in the diagnosis of new cases of pemphigus, as well as to compare the relative sensitivities of monkey oesophagus and normal human skin as substrates for indirect immunofluorescence. These tests were performed on the sera of 29 consecutive new cases of pemphigus diagnosed over a 2-year period based on clinical, histological and direct immunofluorescence findings. Desmoglein enzyme-linked immunosorbent assay was positive in all patients whereas indirect immunofluorescence was positive in only 25 of 29 patients. All four patients with negative indirect immunofluorescence had positive antinuclear antibodies or cytoplasmic fluorescence that could have masked the anti-intercellular antibodies. Desmoglein enzyme-linked immunosorbent assay appeared to reflect the disease activity better than indirect immunofluorescence in a few patients who had active disease of recent onset. Monkey oesophagus was found to be superior or equal to human skin as a substrate for indirect immunofluorescence in both pemphigus vulgaris and foliaceus.

Analyse des signes cliniques des malades atteints de pemphigoïde en fonction des antigènes reconnus par leur sérum en immunotransfert

Clinical features and extent of bullous pemphigoid lesions differed widely among patients. The pathogenic role of anti-BPAG2 antibodies has been recently demonstrated. The aim of this study was to analyze the relationship between clinical features of bullous pemphigoid patients and the antigens recognized by their serum. One hundred and twelve bullous pemphigoid patients were included in this prospective multicenter study. Inclusion criteria were the following: 1) diagnosis of bullous pemphigoid established on the presence of 3 of the 4 clinical features of bullous pemphigoid, histological picture of bullous pemphigoid and positive direct immunofluorescence; 2) serum available for immunoblotting studies. The clinical and biological findings were prospectively recorded on standard forms. Sera were collected and analyzed using indirect immunofluorescence and immunoblotting on human epidermal extracts. Analysis of patient's clinical features depending on the antigens recognized by their serum showed that patients whose serum contained anti-BPAG1 antibodies had more frequently pruritus, blisters on the lower limbs and a positive indirect immunofluorescence. Patients whose serum contained anti-BPAG2 antibodies had blisters more frequently localized on the head, and a more frequently negative indirect immunofluorescence. Patients whose serum was negative by immunoblotting had less frequently urticarial and/or eczematous lesions, bullae less frequently localized on the lower part of the trunk, abdomen and lower limbs, lower eosinophilia and a more frequently negative indirect immunofluorescence. Patients with circulating anti-BPAG1 antibodies exhibited the most typical, clinical and biological features of bullous pemphigoid.

Detection of Specific Antinuclear Reactivities in Patients with Negative Anti-nuclear Antibody Immunofluorescence Screening Tests

For detection of anti-nuclear antibodies (ANAs) and antibodies to extractable nuclear antigens (ENAs), samples frequently are screened with indirect immunofluorescence (IIF); further determination of anti-ENA antibodies is performed only when the result is positive. However, because anti-ENA reactivities are found in samples with low fluorescence intensities, we determined anti-ENA antibodies in samples with negative IIF and thus calculated the sensitivity of IIF for specific ANAs. We collected 494 samples consecutively referred by rheumatologists for routine ANA testing. IIF on HEp-2 and HEp-2000 (HEp-2 cells transfected with Ro60 cDNA) and line immunoassay (LIA) for the detection of specific ANAs were performed on all samples. Fluorescence intensities and patterns on HEp-2 were strongly correlated with those on HEp-2000 [Spearman rho = 0.852 (P <0.001) and 0.838 (P <0.001), respectively]. Sixty-eight of 494 samples were positive on LIA, of which only 72% (confidence interval, 68-76%) were detected with HEp-2 and 75% (confidence interval, 70-78%) with HEp-2000. Of 291 samples negative on both substrates, 12 were positive on LIA. Connective tissue diseases were diagnosed in four of these patients and suspected in at least three others. The HEp-2 and HEp-2000 substrates perform comparably for fluorescence intensities and patterns and for detecting specific ANAs, but some patients with negative IIF show reactivity on LIA. We recommend testing for fine reactivities, regardless of the IIF result, when the clinical suspicion for rheumatic connective tissue disease is high.

Bullous pemphigoid in Liguria: A 2‐year survey

The epidemiology of bullous pemphigoid (BP) is not clear because of the heterogeneity of the disease, and its possible association with internal malignancies has been under debate for many years. We report the findings of a 2-year study on incident BP cases in the Liguria region of Italy. Thirty-two patients with BP were collected over the 2-year period. Diagnosis was made based on clinical findings and confirmed by histology, direct immunofluorescence (DIF) and indirect immunofluorescence (IIF) with salt-split skin and monkey oesophagus, and immunoblotting (IB). All patients were thoroughly investigated for possible malignancies and all were followed up for 6 months to monitor the response to treatment. DIF showed linear deposits at the dermoepidermal junction in all but one patient. IIF gave positive findings for 15 sera tested with monkey oesophagus and 20 tested with salt-split skin. IB gave positive findings in 19 cases. There was a malignancy in six cases, but no clinical or immunological features that could be considered to predict this occurrence. The findings of this study are in accordance with most of the data found in the literature, including the fact that IgG serum levels did not predict the course of the disease. Contrary to previous indications, IgE levels were not indicative of disease course either. Mucosal lesions, erythema multiform-like lesions, negative IIF findings and antibodies to AgPB2 were not a prediction for the development of malignancy.

Mucous membrane pemphigoid: a dual circulating antibody response with IgG and IgA signifies a more severe and persistent disease.

Mucous membrane pemphigoid (MMP) is an autoimmune blistering disease frequently associated with scarring of involved clinical sites. At present, therapeutic intervention in the form of immunomodulating or immunosuppressive agents is often reserved until the onset of significant inflammation and/or early cicatrization. We have therefore studied the clinical and immunopathological findings in 67 patients with MMP in order to try to establish a reliable prognostic indicator by which patients at high risk may be identified early in the disease. Inclusion criteria were a predominantly mucosal disease and the detection of IgG and/or C3 anti-basement membrane zone (BMZ) immunoreactants using immunofluorescence techniques. Patients were allocated to three disease subgroups on the basis of the modality and duration of therapeutic intervention required to achieve effective control of disease. In addition, at presentation and at each follow-up visit, a clinical score for severity of involved clinical sites was awarded and serum collected for indirect immunofluorescence (IIF). A dual circulating anti-basement membrane zone (anti-BMZ) antibody response with IgG and IgA was significantly associated with a more severe and persistent disease profile (P < 0.001). The odds ratios for requiring systemic therapy were: 11.6 among patients in whom there was a clinical score > or = 5 compared with a score < 5, and 31.3 and 66.9 among patients with IgG alone and both IgG and IgA, respectively, compared with negative IIF. The findings suggest that an assessment based upon a combination of site severity score and the presence of circulating IgG and IgA by IIF using 1 mol/L salt-split human skin substrate may be considered a useful prognostic indicator.

Accuracy of indirect immunofluorescence testing in the diagnosis of paraneoplastic pemphigus

Background: Paraneoplastic pemphigus (PNP) is an autoimmune disease defined in part by autoantibodies with unique specificity. Initial reports suggested that indirect immunofluorescence with rodent bladder epithelium was highly reliable in detecting these autoantibodies. Objective: We compared the sensitivity and the specificity of indirect immunofluorescence in the diagnosis of PNP in a large number of cases. Methods: Indirect immunofluorescence was performed on stratified squamous epithelium of monkey esophagus and mouse tongue, bladder, liver, and myocardium. Sera were obtained from 28 patients with PNP and from 29 control subjects with autoimmune blistering diseases. Results: The sensitivity of murine bladder as a substrate was 75%, with a specificity of 83%. Indirect immunofluorescence on liver was specific (96.5%) but insensitive (43%). Sensitivity and specificity with myocardium were intermediate. Conclusion: Indirect immunofluorescence on murine bladder epithelium is an adequate screening test for PNP but is negative or indeterminate in as many as one fourth of patients. Negative indirect immunofluorescence does not exclude the diagnosis of PNP, and immunochemical techniques such as immunoprecipitation must be performed.