Detection of antibodies against the non-calcium-dependent epitopes of desmoglein 3 in pemphigus vulgaris and their pathogenic significance

Pathogenic relevance of antibodies against desmoglein 3 in patients with oral lichen planus

BACKGROUND AND OBJECTIVES

Oral lichen planus (OLP) is a T cell driven disorder that significantly impairs patients' quality of life. Previous reports suggest that both cellular and humoral activities against desmoglein (dsg) 1 and 3 may be involved in OLP pathogenesis. Here, we aim to analyze the frequency of occurrence and pathological significance of anti-dsg antibodies in a large cohort of OLP patients.

MATERIALS AND METHODS

OLP patients were screened for anti-dsg antibodies by enzyme-linked immunosorbent assay in three tertiary referral centers. OLP sera with anti-dsg antibodies were further analyzed by Western blot and dispase-based keratinocyte dissociation assay (DDA) to identify the targeted dsg ectodomains and to assess their pathogenicity.

RESULTS

Of 151-screened individuals with OLP, only four patients (2.6%) with erosive OLP showed serum IgG against dsg1/3. Western blot analysis with recombinant dsg3 ectodomains revealed preferential recognition of the extracellular domain 5. By DDA with spontaneously immortalized human keratinocytes, none of the sera from these four patients induced acantholysis.

CONCLUSIONS

Activation of humoral immunity occurs prevalently in patients with erosive OLP, probably due to epitope spreading. OLP serum antibodies are unable to induce loss of intercellular adhesion in vitro, strongly suggesting that they are not disease causing but rather an epiphenomenon.

Calcium-dependent HLA-DQ epitope revealed by EDTA mediated inhibition of antibody reactions in the Luminex single antigen bead assay

Complement mediated interference with the detection of antibodies targeting HLA is a known limitation of the single antigen bead (SAB) Luminex assay. Ethylenediaminetetraacetic acid (EDTA) is currently the serum treatment of choice in most histocompatibility laboratories to block complement activation by chelating calcium. The purpose of this study was to investigate a serum with an antibody reactivity to HLA-DQ6, 7, 8 and 9 molecules, in the Luminex SAB assay, that was inhibited by treatment with EDTA. Serum was from a 55-year-old highly sensitised female renal transplant candidate that contained, among others, antibodies to an epitope containing the 74EL eplet, shared by HLA-DQ6, DQ7, DQ8 and DQ9 molecules. Serum samples were treated with EDTA, dithiothreitol (DTT), or heat prior to testing by SAB assay. EDTA-treated serum was also tested after the addition of calcium chloride (CaCl2). HLA-DQ-specific antibodies were isolated by adsorption/elution method using three informative donor cells and were tested in the absence or presence of EDTA. The antibody reactivity against HLA-DQ6, DQ7, DQ8 and DQ9 in the SAB assay was significantly inhibited by treating serum and eluates with EDTA and was restored by addition of CaCl2. The study represents the first description of a calcium-dependent epitope in HLA molecules. The relevance of this finding is that the treatment of sera with EDTA could lead to false-negative reactions in the SAB assay, which may compromise virtual crossmatching.

Two cases of cutaneous-type pemphigus vulgaris and a case of pemphigus foliaceus without mucosal involvement despite high anti-desmoglein 3 autoantibody levels

Pemphigus is an autoimmune blistering disease with two major subtypes, pemphigus vulgaris (PV) and pemphigus foliaceus (PF). Although most patients with PV show oral lesions, cutaneous type PV (C-PV) is a rare subtype clinically characterized by predominant cutaneous involvement with no or subtle mucosal lesions. Patients with PF present with only skin involvement; they do not have mucosal lesions. Serologically, autoantibodies against desmoglein (Dsg) 3 and Dsg1 are observed in C-PV whereas PF is associated with anti-Dsg1 antibodies only. Herein, we describe three cases of pemphigus presenting with predominant skin lesions and no mucosal involvement despite high anti-Dsg 3 autoantibody levels in chemiluminescent enzyme immune assays (CLEIAs). In addition, anti-Dsg 1 autoantibodies were positive in patients 2 and 3, but negative in patient 1 based on CLEIAs. Histological examination of the skin showed suprabasal acantholysis in patients 1 and 2, and blister formation in the upper epidermis in patient 3. Histopathology of the oral membrane in patients 1 and 2 showed subtle acantholysis in the suprabasal layer. Thus, we diagnosed patients 1 and 2 as having cutaneous type PV and patient 3 as having PF. Ethylenediaminetetraacetic acid-treated enzyme-linked immunosorbent assay demonstrated a low proportion of anti-Dsg3 autoantibodies recognizing Ca2+ -dependent epitopes, antibodies against which are thought to be the main contributor to acantholysis. Thus, along with Dsg1 antibodies, weak anti-Dsg3 antibodies could induce acantholysis in the skin, but they are insufficient to induce mucosal lesions.

IgG against the Membrane-Proximal Portion of the Desmoglein 3 Ectodomain Induces Loss of Keratinocyte Adhesion, a Hallmark in Pemphigus Vulgaris

Pemphigus vulgaris is a severe autoimmune blistering disease characterized by IgG autoantibodies (auto-abs) against the desmosomal adhesion molecules desmoglein (DSG) 3 and DSG1. Underlying mechanisms leading to blister formation upon binding of DSG-specific IgG auto-abs are not fully understood. Numerous studies showed the pathogenicity of IgG auto-ab binding to the aminoterminal region 1 (EC1) of the DSG3 ectodomain. However, auto-abs in pemphigus vulgaris are polyclonal, including IgG against both aminoterminal- and membrane-proximal epitopes of the DSG3 ectodomain. In this study, the pathogenicity of a previously uncharacterized murine monoclonal IgG antibody, 2G4, directed against the membrane-proximal region (EC5) of the DSG3 ectodomain was characterized and tested in various specificity and functionality assays. The results clearly show that 2G4 is capable of inhibiting intercellular keratinocyte adhesion and of inducing cellular DSG3 redistribution by activation of the p38MAPK signal transduction pathway. In this study, we provide evidence that an IgG auto-abs directed against the membrane-proximal region EC5 of DSG3 induces acantholysis, the hallmark in pemphigus vulgaris. These findings challenge the current concept that IgG auto-abs targeting the NH₂-terminal portion of the DSG3 ectodomain are pathogenic only. Our study provides further aspects for a deeper understanding of desmosomal keratinocyte adhesion and improves our insight into the complex auto-ab‒induced blister formation in pemphigus vulgaris.

Dsg3 epitope-specific signalling in pemphigus

Introduction

Pemphigus is an autoantibody driven disease that impairs the barrier function of the skin and mucosa by disrupting desmosomes and thereby impeding cellular cohesion. It is known that the different clinical phenotypes of pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are dependent on the autoantibody profile and target antigens that, amongst others, are primarily desmoglein (Dsg)1 and/or Dsg3 for PV and Dsg1 for PF. However, it was reported that autoantibodiesagainst different epitopes of Dsg1 and Dsg3 can be pathogenic or not. The underlying mechanisms are very complex and involve both direct inhibition of Dsg interactions and downstream signalling. The aim of this study was to find out whether there is target-epitope-specific Dsg3 signalling by comparing the effects of the two pathogenic murine IgGs, 2G4 and AK23.

Methods

Dispase-based dissociation assay, Western Blot analysis, Stimulated emission depletion microscopy, Fura-based Ca2+ flux measurements, Rho/Rac G-Protein-linked immunosorbent assay, Enzyme-linked immunosorbent assay.

Results

The IgGs are directed against the EC5 and EC1 domain of Dsg3, respectively. The data show that 2G4 was less effective in causing loss of cell adhesion, compared to AK23. STED imaging revealed that both autoantibodies had similar effects on keratin retraction and reduction of desmosome number whereas only AK23 induced Dsg3 depletion. Moreover, both antibodies induced phosphorylation of p38MAPK and Akt whereas Src was phosphorylated upon treatment with AK23 only. Interestingly, Src and Akt activation were p38MAPK-dependent. All pathogenic effects were rescued by p38MAPK inhibition and AK23-mediated effects were also ameliorated by Src inhibition.

Discussion

The results give first insights into pemphigus autoantibody-induced Dsg3 epitope-specific signalling which is involved in pathogenic events such as Dsg3 depletion.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

Pemphigus represents a group of rare and severe autoimmune intra-epidermal blistering diseases affecting the skin and mucous membranes. These painful and debilitating diseases are driven by the production of autoantibodies that are mainly directed against the desmosomal adhesion proteins, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). The search to define underlying triggers for anti-Dsg-antibody production has revealed genetic, environmental, and possible vaccine-driven factors, but our knowledge of the processes underlying disease initiation and pathology remains incomplete. Recent studies point to an important role of T cells in supporting auto-antibody production; yet the involvement of the myeloid compartment remains unexplored. Clinical management of pemphigus is beginning to move away from broad-spectrum immunosuppression and towards B-cell-targeted therapies, which reduce many patients’ symptoms but can have significant side effects. Here, we review the latest developments in our understanding of the predisposing factors/conditions of pemphigus, the underlying pathogenic mechanisms, and new and emerging therapies to treat these devastating diseases.

Pemphigus patients with initial negative levels of anti- desmoglein; a subtype with different profile?

BACKGROUND

Pemphigus is a blistering autoimmune disease that is characterized by autoantibodies against desmoglins (Dsg), including anti-Dsg1 and anti-Dsg3. Despite the diagnosis of diseases, the anti-Dsg test by Enzyme-linked immunosorbent assay (ELISA) is negative in a small group of pemphigus patients. The aim of this study was to evaluate the clinical course, clinical symptoms, and response to treatment in pemphigus patients with negative levels of anti-Dsg1 and anti-Dsg3.

METHODS

In this study, the data of pemphigus patients referred to Razi Hospital were retrospectively collected from the medical records from 2016 to 2020. Eight patients, whose initial anti-Dsg1/anti-Dsg3 was negative by the ELISA test, were enrolled and their clinical course, clinical signs, and response to treatment were evaluated.

RESULTS

The mean age of the subjects (8 females) was 38.75±12.09. The most common phenotype of the subjects was pemphigus vulgaris (PV) with mucosal involvement. Additionally, the common site of blister inception was mouth of the patients. The mean prednisolone dose received by the patients at the initiation was 32.5±13.62 mg/day. According to Pemphigus Disease Area Index (PDAI), 6 patients had mild severity, wile 2 cases had moderate severity. Among the patients, 6 subjects received rituximab (RTX). Also, 5 patients experienced remission after 6.2±5.21 months.

CONCLUSION

PV is the most common phenotype of the disease and mucosal involvement is more common in patients with negative anti-Dsg-1/3 results. The severity of the lesions in most of the patients is mild at baseline and most patients seems to respond to RTX therapy and reach remission.

Analysis of clinical characteristics, prognosis and antibody pathogenicity of pemphigus patients positive for anti-desmoglein IgG autoantibodies in remission: a retrospective cohort study

BACKGROUND

The detection of serum anti-desmoglein (Dsg) IgG autoantibodies has been reported to be useful for assessment of disease activity in pemphigus. However, previous studies have reported that anti-Dsg autoantibodies remain detectable in some patients without active pemphigus lesions.

OBJECTIVES

To investigate the clinical characteristics and antibody pathogenicity of pemphigus patients positive for anti-Dsg IgG autoantibodies in remission.

METHODS

We retrospectively investigated pemphigus patients with a history of clinical remission who visited the Department of Dermatology of Keio University during 2019 and 2020. The antibody pathogenicity was assessed by bead aggregation assay.

RESULTS

When patients were recognized as having entered remission (PDAI = 0 and PSL ≦ 10 mg/day for 2 months), serum autoantibodies against Dsg were detected in 72 of 132 patients (54.5%, positive group; PG), but were not detected in 60 patients (45.5%, negative group; NG). Anti-Dsg antibody titres in remission declined from the active phase in 33 patients in the PG for whom data were available. There were no differences in the chance of reducing PSL to 5 mg/day (P = 0.885) and rate of relapse (P = 0.279) between PG and NG, but fewer patients in PG discontinued corticosteroids (P = 0.004). The ability of patients' sera to block aggregation of Dsg/desmocollin beads was significantly reduced in remission compared to the active phase. However, our results revealed that whole sera in remission still had pathogenic activity in seven of nine patients, and the approximately equal amounts of anti-Dsg antibodies in active phase and remission showed similar pathogenicity.

CONCLUSIONS

This study will provide guidance in cases where autoantibodies are found to be positive in pemphigus patients during remission or steroid reduction.

Autoantibodies against Desmoglein 1 and 3 in South Tunisian pemphigus

BACKGROUND

Desmoglein (Dsg) 1 and 3 are the 2 major autoantigens in pemphigus foliaceus (PF) and pemphigus vulgaris (PV).

AIM

We aimed to determine anti-Dsg1 and 3 Abs'usefulness in the diagnosis of pemphigus and to assess the correlation of these antibodies (Abs) with clinical phenotype and disease activity in south Tunisian patients.

METHODS

We retrospectively analyzed 131 samples from 82 patients (52 with PF and 30 with PV) during follow-up. Anti-Dsg1 and 3 Abs were measured by ELISA. Consecutive anti-Dsg1 and 3 Abs were correlated with disease activity. Receiver operating characteristics (ROC) curve were calculated to determine anti-Dsg1 and 3 Abs'cut-offs with optimal sensitivity and specificity for disease activity.

RESULTS

Anti-Dsg1 and 3 levels were associated to in PF and PV patients respectively (p<0,001). Anti-Dsg1 and 3 Ab were associated with skin (95%) and mucosal (60%) lesions, respectively. A significant decrease of anti-Dsg1 Abs was observed in patients with PF in clinical remission (36 ± 62 U/mL; (p=0,04). No correlation was found between anti-Dsg3 Abs and the course of mucosal lesions in PV (p=0,3). During follow-up, anti-Dsg1 Abs correlated with relapses (177 ±60 U/mL ; p=0,04). The 161,5 U/mL cut-off for anti-Dsg1 Abs provided 100% specificity and 86,4% sensitivity in PF disease activity. The 30,7U/mL cut-off for anti-Dsg3 provided 89,5% sensitivity and 100% specificity in PV.

CONCLUSIONS

High anti-Dsg3 Abs values are not always associated with PV disease activity. Anti-Dsg1 Abs showed a closer relationship with skin activity in PS and should be therefore taken into account in management of pemphigus patients.

Evaluation of the pathogenicity of anti-desmoglein antibodies of pemphigus vulgaris patients using human organ culture assay

Anti-desmoglein (anti-Dsg) antibodies are key players in the pathogenesis of pemphigus vulgaris (PV) disease. We aimed to evaluate the pathogenicity of anti-Dsg antibodies of PV patients using human organ culture assay and to assess the correlation between the pathogenicity and the disease score. In this cross-sectional study, sera from 37 PV patients were included. The organ culture acantholysis index (OCAI) was calculated as (width of blister/total width of the specimen) × 100. The sera were analyzed using Dsg ELISAs and ethylenediaminetetraacetic acid (EDTA) treated ELISAs. OCAI ranged from 0 to 100%, median = 50%. There was a moderate significant correlation between OCAI and the disease severity, r = 0.503, p = 0.002. There was a moderate significant correlation between OCAI and non-Ca²⁺-dependent anti-Dsg3 and anti-Dsg1 antibodies, p values were 0.01 and 0.021, respectively. The OCAI was assessed along the disease time course of four patients. The OCAI fluctuated parallel to the disease severity along the time course of the four patients. Human organ culture assay is an objective tool that detects the pathogenicity of anti-desmoglein antibodies. It can be used before stopping systemic steroids especially in patients in remission with high titer or if the Dsg ELISA is not available.

Short-term clinical and serological follow-up with conventional and conformational anti-desmoglein antibodies in treatment-naïve and previously treated patients with pemphigus vulgaris after receiving rituximab

Background

Pemphigus vulgaris (PV) is a blistering, life-threatening autoimmune disease. Ethylenediaminetetraacetic acid (EDTA)-treated desmoglein (Dsg) enzyme-linked immunosorbent assay (ELISA) has recently been suggested to detect nonpathogenic antibodies. Rituximab (RTX) is now considered a first-line treatment for PV.

Objective

The primary and secondary aims were to evaluate anti-Dsg and EDTA-treated anti-Dsg ELISA and clinical response before and 3 months after RTX in treatment-naïve and previously treated patients, respectively. In addition, we compared the short-term efficacy of RTX between these groups.

Methods

Seventy-five patients with PV who received RTX (500 mg weekly for 4 weeks or 1000 mg 2 weeks apart) and prednisolone were followed for 3 months. Thirty-seven treatment-naïve newly diagnosed (group A) and 38 relapsed patients (group B) were included. Disease activity was scored with the Pemphigus Disease Area Index (PDAI). Clinical response was also assessed. Serum samples were collected at two points and examined for anti-Dsg1/3 and EDTA-treated anti-Dsg1/3. Conformational anti-Dsg values were calculated by subtracting EDTA-treated from conventional anti-Dsg values.

Results

The correlation of conventional and conformational anti-Dsg values was perfect (correlation coefficient > 0.98; p < .001) at every time point for both anti-Dsgs. There was no difference with regard to PDAI and anti-Dsg values between the two groups at baseline. The frequency of responders was significantly higher in group A (100%) than in group B (89%; p = .006). Three patients relapsed, and five patients had persistent disease activity in group B. After 3 months, conventional and conformational anti-Dsg values were significantly higher in group B compared with group A (anti-Dsg3: p = .017 and .021, respectively; anti-Dsg1: p = .014 and .016, respectively). Total and scalp PDAI were significantly lower in group A than in group B (p = .042 and .016, respectively).

Conclusion

EDTA-treated anti-Dsg ELISA had no added value. Using RTX as first-line treatment in patients with PV appears to be associated with better clinical response and immunologic profile than delayed treatment in the short term.

Monopathogenic vs multipathogenic explanations of pemphigus pathophysiology

This viewpoint highlights major, partly controversial concepts about the pathogenesis of pemphigus. The monopathogenic theory explains intra-epidermal blistering through the "desmoglein (Dsg) compensation" hypothesis, according to which an antibody-dependent disabling of Dsg 1- and/or Dsg 3-mediated cell-cell attachments of keratinocytes (KCs) is sufficient to disrupt epidermal integrity and cause blistering. The multipathogenic theory explains intra-epidermal blistering through the "multiple hit" hypothesis stating that a simultaneous and synchronized inactivation of the physiological mechanisms regulating and/or mediating intercellular adhesion of KCs is necessary to disrupt epidermal integrity. The major premise for a multipathogenic theory is that a single type of autoantibody induces only reversible changes, so that affected KCs can recover due to a self-repair. The damage, however, becomes irreversible when the salvage pathway and/or other cell functions are altered by a partnering autoantibody and/or other pathogenic factors. Future studies are needed to (i) corroborate these findings, (ii) characterize in detail patient populations with non-Dsg-specific autoantibodies, and (iii) determine the extent of the contribution of non-Dsg antibodies in disease pathophysiology.

Evaluation of anti-desmoglein-1 and anti-desmoglein-3 autoantibody titers in pemphigus patients at the time of the initial diagnosis and after clinical remission

It has been suggested that anti-desmoglein autoantibody titers could be helpful in follow-up and therapeutic management of pemphigus patients. However, there is no consensus regarding the relationship between anti-desmoglein autoantibody titers and clinical activity of pemphigus.The aim of our study was to evaluate if clinical remission of pemphigus relates to the presence of anti-desmoglein autoantibodies.Thirty patients with pemphigus vulgaris and 7 patients with pemphigus foliaceous were included in the study. Assessment of autoantibody titers was carried out at the time of the initial diagnosis and after the clinical remission using an enzyme-linked immunosorbent assay-based assay.Our results indicate that pemphigus clinical remission did not necessarily imply a serological remission, and consequently it is necessary to establish if withdrawal of the immunosuppressive regimen in pemphigus should be based exclusively on the achievement of clinical remission or also on the serological findings.

Autoantibodies to desmogleins 1 and 3 in patients with lichen planus

There is controversy about the role of autoantibodies against desmoglein 1 and 3 (Dsg1 and 3) in the pathogenesis of lichen planus (LP); the authors planned this study to determine the presence of circulating levels of these antibodies in patients with different types of oral LP and to compare that with cutaneous LP and healthy controls. The enzyme-linked immunosorbent assay test was performed on serum samples of 24 cases of erosive oral LP, 29 cases of reticular oral LP, 30 cases of cutaneous LP and 30 healthy controls. The severity of oral LP was evaluated by Reticulation, Erosion and Ulceration scoring system. There were no significant differences in the concentrations of autoantibodies to Dsg1 between the four groups. Autoantibodies to Dsg3 were increased in erosive oral LP compared with healthy controls (p value = 0.005) but no increase was observed between other groups. We did not detect a correlation between the severity of the disease and the levels of anti-Dsg1 and 3 in patients with erosive and reticular types of oral LP. In conclusion, regardless of the increased level of anti-Dsg3 antibody in erosive oral LP, serum concentrations of antibodies were under cut-off values. Moreover, the pathogenic role of anti-Dsg3 antibodies in erosive oral LP is uncertain.

Possible enhancement of BP180 autoantibody production by herpes zoster

Bullous pemphigoid (BP) is an autoimmune blistering disease caused by autoantibodies against type XVII collagen/BP180 (BP180). Although the mechanisms of autoantibody production remain to be elucidated, herpes virus infections have been identified as a possible triggering factor for pemphigus. We report a case of herpes zoster (HZ) having anti-BP180 serum antibodies. The patient developed sudden-onset, tense blisters and edematous erythema on the right anterior chest, shoulder and upper back. Histopathology showed remarkable degeneration of keratinocytes, acantholysis and blister formation with ballooning cells, indicating herpes virus infection. A polymerase chain reaction analysis of varicella zoster virus (VZV) was positive in crusts and effusions from the skin lesions, confirming the definitive diagnosis of HZ. Notably, we found that the patient had anti-BP180 serum antibodies in association with the occurrence of HZ. After successful treatment with valacyclovir hydrochloride for 7 days, the serum levels of anti-BP180 antibodies decreased in accordance with the improvement of skin lesions. These findings suggest that the production of anti-BP180 antibodies could be triggered by the reactivation of VZV.

A higher correlation of the antibody activities against the calcium-dependent epitopes of desmoglein 3 quantified by ethylenediaminetetraacetic acid-treated enzyme-linked immunosorbent assay with clinical disease activities of pemphigus vulgaris

BACKGROUND

Nonpathogenic anti-desmoglein (Dsg) 3 antibodies can be found in pemphigus vulgaris (PV) patients' sera. Previously, ethylenediaminetetraacetic acid (EDTA)-treated enzyme-linked immunosorbent assay (ELISA) was found to detect only nonpathogenic anti-Dsg3 antibodies against the non-calcium (Ca(2+))-dependent epitopes.

OBJECTIVE

We examined whether the calculated anti-Dsg3 antibody titer for Ca(2+)-dependent epitopes, using the conventional and EDTA-treated ELISAs, correlated better with the disease activity of PV.

METHODS

We analyzed 123 serum samples from 19 PV patients. Of these samples, there were 52 samples from 15 PV patients obtained in asymptomatic phases. The difference between conventional Dsg3 ELISA index and EDTA-treated Dsg3 ELISA index was calculated as the anti-Dsg3 antibody activity for Ca(2+)-dependent conformational epitopes (conformational Dsg3 ELISA index). We analyzed the correlation between Dsg3 ELISA index values and the pemphigus disease area index (PDAI). Moreover, we examined whether the conformational Dsg3 ELISA index fluctuated in parallel with the disease activity during clinical courses of 6 PV patients. We evaluated the pathogenicity of anti-Dsg3 antibodies detected in remission phases using a dissociation assay.

RESULTS

The conventional Dsg3 ELISA index showed a high positive rate in the asymptomatic phase of PV. By contrast, the conformational Dsg3 ELISA index showed a much closer correlation to the disease activity when monitored in individual cases. Nonpathogenic anti-Dsg3 antibodies were detected in these cases.

CONCLUSION

The conformational Dsg3 ELISA index reflected the pathogenicity of anti-Dsg3 antibodies more accurately than the conventional Dsg3 ELISA index. Using both conventional and EDTA-treated ELISAs would be useful in monitoring the disease activity of PV.

Pemphigus vulgaris autoantibody profiling by proteomic technique

Pemphigus vulgaris (PV) is a mucocutaneous blistering disease characterized by IgG autoantibodies against the stratified squamous epithelium. Current understanding of PV pathophysiology does not explain the mechanism of acantholysis in patients lacking desmoglein antibodies, which justifies a search for novel targets of pemphigus autoimmunity. We tested 264 pemphigus and 138 normal control sera on the multiplexed protein array platform containing 701 human genes encompassing many known keratinocyte cell-surface molecules and members of protein families targeted by organ-non-specific PV antibodies. The top 10 antigens recognized by the majority of test patients’ sera were proteins encoded by the DSC1, DSC3, ATP2C1, PKP3, CHRM3, COL21A1, ANXA8L1, CD88 and CHRNE genes. The most common combinations of target antigens included at least one of the adhesion molecules DSC1, DSC3 or PKP3 and/or the acetylcholine receptor CHRM3 or CHRNE with or without the MHC class II antigen DRA. To identify the PV antibodies most specific to the disease process, we sorted the data based on the ratio of patient to control frequencies of antigen recognition. The frequency of antigen recognition by patients that exceeded that of control by 10 and more times were the molecules encoded by the CD33, GP1BA, CHRND, SLC36A4, CD1B, CD32, CDH8, CDH9, PMP22 and HLA-E genes as well as mitochondrial proteins encoded by the NDUFS1, CYB5B, SOD2, PDHA1 and FH genes. The highest specificity to PV showed combinations of autoantibodies to the calcium pump encoded by ATP2C1 with C5a receptor plus DSC1 or DSC3 or HLA-DRA. The results identified new targets of pemphigus autoimmunity. Novel autoantibody signatures may help explain individual variations in disease severity and treatment response, and serve as sensitive and specific biomarkers for new diagnostic assays in PV patients.