Pemphigus Antibodies Research Articles

Autoantibodies to DSC3 in Pemphigus Exclusively Recognize Calcium-Dependent Epitope in Extracellular Domain 2

Pemphigus is a group of autoimmune bullous diseases characterized by the presence of autoantibodies against adhesion molecules, desmogleins, and desmocollins (DSCs). The pathogenicity of anti-DSC3 antibodies in pemphigus has been demonstrated; however, its characteristics have not yet been elucidated. We aimed to analyze the characteristics of anti-DSC3 antibodies using DSC3 domain‒swapped desmoglein 2 molecules in which the prosequence and five extracellular (EC) domains of desmoglein 2 were replaced with the corresponding domains of human DSC3. Using these proteins, we established an ELISA and analyzed sera from 56 patients with pemphigus. In 34 pemphigus sera positive for DSC3 full-EC domains, 15 sera (44.1%) were positive for EC2 domain, whereas other domains were rarely positive. We assessed the reactivity to a calcium-dependent epitope in DSC3 by ELISA with EDTA. The reactivity with the EC2 domain was mostly compromised in the presence of EDTA. In the invitro assay, IgG from patients with paraneoplastic pemphigus preadsorbed with EC2 prevented both reduction of DSC3 and keratinocyte dissociation as compared with that with EDTA-treated EC2. This study revealed a predominant recognition of calcium-dependent epitopes in EC2 domain by anti-DSC3 antibodies and its pathogenicity on keratinocyte adhesion through DSC3 depletion.

Serum Detection of Anti-thyroid Peroxidase and Anti-thyroglobulin Antibodies in Chinese Patients With Pemphigus Vulgaris and Pemphigus Foliaceus and Literature Review.

BackgroundPemphigus is a rare but life-threatening autoimmune skin disease characterized by blistering on skin and/or mucous membranes. The physiological process of blister formation involves IgG antibodies against the desmogleins (Dsgs) and desmocollins (Dscs). Additional autoAbs have also been suggested to mediate the disease heterogeneity, such as anti-thyroid peroxidase (anti-TPO) and antithyroglobulin (anti-Tg) antibodies, the essential culprits of the immune system in autoimmune thyroid diseases.PurposeTo investigate the levels and antibody positivity of anti-TPO and anti-Tg antibodies in pemphigus patients.MethodsAntibody positivity and levels of anti-TPO and anti-Tg antibodies in pemphigus patients as compared to healthy controls were examined. A meta-analysis was conducted by reviewing six similar studies.Results98 Chinese pemphigus patients and 65 healthy controls were enrolled in the study. Our meta-analysis revealed a significant correlation between increased presence of positive anti-TPO and anti-Tg antibodies and pemphigus, particularly for pemphigus vulgaris (PV). Such correlation was also observed in our own hospitalized PV patients, but not in pemphigus foliaceus (PF) patients. In addition, the status of anti-TPO and anti-Tg antibodies were also compared between females and males within PV patients, PF patients or controls, as well as compared for females or males between pemphigus patients and controls. In the analysis of T cell counts, we found abnormal low CD3 + T cell counts (< 690 n/µl) were only detected in patients whose thyroid antibody levels were less than 20 IU/ml.ConclusionPemphigus patients showed higher levels and antibody positivity of anti-TPO and anti-Tg antibodies than healthy controls. Further investigations are needed to identify the pathogenic functions of these antibodies in pemphigus, as well as to identify the potential shared susceptibility genes.

An Atypical Presentation of Pemphigus Vegetans in the Umbilicus

Pemphigus is a chronic, autoimmune bullous disease that affects the skin and mucous membranes. Pemphigus vegetans is a rare variant of pemphigus and presents as oral ulcerations with associated verrucous lesions in intertriginous or flexural areas. A 38-year-old African American woman presented to the clinic with a chief complaint of oral ulcers. She carried a diagnosis of Behcet’s disease and was referred by rheumatology for evaluation of treatment-resistant mucosal ulcerations. At the time of her dermatology visit, she also reported an enlarging umbilical mass that had been present for several months. Further examination of the umbilical lesion identified an exophytic, vegetative mass. Histologic assessment of the lesion identified acanthosis and acantholysis with dermal eosinophils consistent with pemphigus vegetans. A pemphigus antibody panel was done and resulted positive for IgG desmoglein-3 antibodies. The patient was treated with prednisone and rituximab with improvement of her lesions. We present an atypical presentation of pemphigus vegetans involving the umbilicus. This diagnosis should be considered in patients who present with oral erosions and concomitant vegetative lesions, regardless of location or prior diagnoses.

Factors Associated With Short-term Relapse in Patients With Pemphigus Who Receive Rituximab as First-line Therapy

Rituximab and short-term corticosteroid therapy are the criterion standard treatments for patients with newly diagnosed moderate to severe pemphigus. To examine factors associated with short-term relapse in patients with pemphigus treated with rituximab. This post hoc analysis of a randomized clinical trial (Comparison Between Rituximab Treatment and Oral Corticosteroid Treatment in Patients With Pemphigus [RITUX 3]) conducted from January 1, 2010, to December 31, 2015, included patients from 20 dermatology departments of tertiary care centers in France from the RITUX 3 trial and 3 newly diagnosed patients treated according to the trial protocol. Data analysis was performed from February 1 to June 30, 2019. Patients randomly assigned to the rituximab group in the RITUX 3 trial and the 3 additional patients were treated with 1000 mg of intravenous rituximab on days 0 and 14 and 500 mg at months 12 and 18 combined with a short-term prednisone regimen. Baseline (pretreatment) clinical and biological characteristics (Pemphigus Disease Area Index [PDAI] score, ranging from 0-250 points, with higher values indicating more severe disease) and changes in anti-desmoglein (DSG) 1 and anti-DSG3 values as measured by enzyme-linked immunosorbent assay during the 3 months after rituximab treatment were compared between patients with disease relapse and those who maintained clinical remission during the first 12 months after treatment. The positive and negative predictive values of these factors were calculated. Among 47 patients (mean [SD] age, 54.3 [17.0] years; 17 [36%] male and 30 [64%] female) included in the study, the mean (SD) baseline PDAI score for patients with relapsing disease was higher than that of the patients with nonrelapsing disease (54 [33] vs 28 [24]; P = .03). At month 3, 7 of 11 patients with relapsing disease (64%) vs 7 of 36 patients with nonrelapsing disease (19%) had persistent anti-DSG1 antibody values of 20 IU/mL or higher and/or anti-DSG3 antibody values of 130 IU/mL or higher (P = .01). A PDAI score of 45 or higher defining severe pemphigus and/or persistent anti-DSG1 antibody values of 20 IU/mL or higher and/or anti-DSG3 antibody values of 130 IU/mL or higher at month 3 provided a positive predictive value of 50% (95% CI, 27%-73%) and a negative predictive value of 94% (95% CI, 73%-100%) for the occurrence of relapse after rituximab. The findings suggest that initial PDAI score and changes in anti-DSG antibody values after the initial cycle of rituximab might help differentiate a subgroup of patients with high risk of relapse who might benefit from maintenance rituximab infusion at month 6 from a subgroup of patients with low risk of relapse who do not need early maintenance therapy. NCT00784589.

Pemphigus Vulgaris and Foliaceus IgG Autoantibodies Directly Block Heterophilic Transinteraction between Desmoglein and Desmocollin

Anti-desmoglein (Dsg) 1 and Dsg3 IgG autoantibodies in pemphigus foliaceus and pemphigus vulgaris cause blisters through loss of desmosomal adhesion. It is controversial whether blister formation is due to direct inhibition of Dsg, intracellular signaling events causing desmosome destabilization, or both. Recent studies show that heterophilic binding between Dsg and desmocollin (Dsc) is the fundamental adhesive unit of desmosomes. To eliminate cellular contributions to potential pathogenicity of pemphigus antibodies, bead assays coated with recombinant Dsg1, Dsc1, Dsg3, or Dsc3 ectodomains were developed. A mixture of Dsg beads and Dsc beads formed large aggregates, confirming that the heterophilic binding is dominant. The pathogenic anti-Dsg1 and anti-Dsg3 mAbs, which bind the transadhesive interface, blocked the aggregation of Dsg1/Dsc1 and Dsg3/Dsc3 beads, respectively, whereas nonpathogenic mAbs did not. All sera tested from eight patients with pemphigus foliaceus and eight patients with mucosal pemphigus vulgaris with active disease inhibited the adhesion of Dsg1/Dsc1 and Dsg3/Dsc3 beads, respectively. When paired sera obtained from seven patients with pemphigus foliaceus and six patients with pemphigus vulgaris in active disease and remission were compared, the former inhibited aggregation better than the latter. These findings strongly suggest that steric hindrance of heterophilic transinteraction between Dsg and Dsc is important for disease pathology in both pemphigus foliaceus and pemphigus vulgaris.

A New Solid-Phase Immunosorbent for Selective Binding of Desmoglein 3 Autoantibodies in Patients with Pemphigus Vulgaris.

Autoantibodies, immunoglobulins G (IgG) against the desmosomal proteins desmogleins 1 and 3, play a significant role in the pathogenesis of pemphigus vulgaris. The basic therapy for pemfigus includes systemic corticosteroids, but their use should be as brief as possible because of the severe side effects. In cases of corticosteroid- resistant pemfigus, adjuvant therapy, in particular extracorporeal methods, is used. The most effective and safest extracorporeal therapy is immunosorbtion. Immunosorbtion is based on the removal of pemphigus antibodies from the blood using an affinity sorbent during a therapeutic apheresis procedure. Existing immunosorbents are nonselective and increase the risk of infection. We designed an immunosorbent based on an agarose matrix, Affi-Gel 15, and human recombinant desmoglein 3, as a ligand, for a selective removal of autoantibodies from pemphigus patients’ sera. It was shown on a pemphigus experimental model in vivo (neonatal Balb/c mouse model) and in vitro that the immunosorbent can effectively remove desmoglein 3-associated autoantibodies. The experimental results demonstrate that the solid-phase matrix immunosorbent Affi-Gel 15–Dsg3 is a promising product for the development of pemphigus therapy.

Locations of acantholysis in 71 cases of pemphigus

Objective To analyze locations of acantholysis in pemphigus vulgaris (PV) and pemphigus foliaceus (PF) , so as to explain why acantholysis in pemphigus occurs in different locations of the epidermis. Methods Clinical data, histopathological and immunopathological findings, and pemphigus antibody level values were collected from 43 patients with PV and 28 with PF, and retrospectively analyzed. Results Of the 43 patients with PV, 35 showed acantholysis in the upper basal layer, 8 in the middle-to-upper epidermis. Of the 28 patients with PF, 25 showed acantholysis in the granular layer and the upper prickle cell layer, 3 in the middle-to-lower epidermis. Patients with PF showed significantly higher levels of anti-Desmoglein 1 (Dsg1) antibody compared with patients with PV (P= 0.047) . However, there were no significant differences in the levels of anti-Dsg1 and anti-Dsg3 antibodies between PV patients who had acantholysis in the middle-to-upper epidermis and those in the upper basal layer. Conclusion Histopatho-logical examinations of PV and PF lesions show that acantholysis can occur in the middle-to-upper epidermis, as well as in the middle-to-lower epidermis, and locations of acantholysis may be associated with levels of anti-Dsg1 and anti-Dsg3 antibodies. Key words: Pemphigus; Acantholysis; Desmoglein 1; Desmoglein 3; Antibodies; Enzyme-linked immunosorbent assay

Relationship between pemphigus and American tegumentary leishmaniasis: insights from serological and genetic profiles.

Antibodies against Leishmania peptides (Lbr-peps) and desmogleins (Dsgs) have been reported in pemphigus foliaceus (PF) and leishmaniasis patients, respectively. We aimed to compare serological and genetic features in a Brazilian region endemic for American tegumentary leishmaniasis (ATL) and pemphigus. Commercial anti-Dsg ELISA and in-house ELISA with Lbr-peps were used to determine the serological profile, in addition to immunoblotting (IB) and indirect immunofluorescence (IIF) assays. HLA-DRB1 and -DQA1/DQB1 alleles were characterized by PCR combined with sequence-specific oligonucleotide probes (PCR-SSOP). The serological and genetic profiles were compared using 78 PF, 62 pemphigus vulgaris (PV) and 58 ATL patients against 163 and 1592 healthy controls, respectively. Some ATL patients showed positive results for anti-Dsg1 and/or anti-Dsg3 antibodies. They also revealed 130, 160 and/or 230 kDa epidermal peptides in IB. Moreover, some ATL samples exhibited pemphigus or a bullous pemphigoid pattern in IIF. ELISA and IB assays showed Lbr-peps in pemphigus patients. HLA-DQA1*01 and -DQA1*01:02 were protective and susceptibility alleles for ATL, respectively, but the opposite for pemphigus. Anti-Dsgs in ATL may represent epiphenomena. Anti-Lbr-pep antibodies in pemphigus suggest a previous infection. A differential association of the HLA profile may contribute to the lack of co-association between pemphigus and ATL.

Increase of psoriasis-associated IL-8 in the intralesional blood despite undetectable in the peripheral blood

Skin diseases are often associated with changes in the circulating mediators, including immune cells and soluble factors such as antibodies and cytokines. Some skin diseases occur in response to systemic mediators; for example, anti-desmoglein antibodies in pemphigus. In turn, mediators produced by skin lesions were also detected in the peripheral blood (PB) via diffusion; for example, TARC in atopic eczema. However, we frequently have difficulties to detect lesional skin-derived mediators in PB because of dilution. In this study, we examined cytokines in the intralesional blood (ILB) in comparison of them in PB.

Collaboration between dermatologists and dentists in autoimmune bullous diseases and immunoglobulin A antibodies in pemphigus.

Collaboration between dermatologists and dentists in autoimmune bullous diseases and immunoglobulin A antibodies in pemphigus.

Anti-desmocollin autoantibodies in nonclassical pemphigus.

Despite the established pathogenic role of anti-desmoglein (Dsg) antibodies in classical pemphigus, the significance of autoantibodies to another desmosomal cadherin, desmocollin (Dsc) is at present unknown. No consistent immunoassay for immunoglobulin (Ig) G autoantibodies to Dscs has been developed. The aim of this study was to develop reliable assays to detect anti-Dsc autoantibodies. We expressed soluble recombinant proteins (RPs) of human Dsc1-3 in mammalian cells and examined sera of various types of pemphigus, including 79 paraneoplastic pemphigus (PNP) sera, by novel enzyme-linked immunosorbent assays (ELISAs) using the RPs. We also performed ELISAs of Dsc baculoproteins and used the complementary DNA (cDNA) transfection method, and compared the results with those of mammalian ELISAs. Through mammalian ELISAs, IgG autoantibodies to Dsc1, Dsc2 and Dsc3 were detected in 16.5%, 36.7% and 59.5% of PNP sera, respectively, and considerable numbers of pemphigus herpetiformis (PH) and pemphigus vegetans (PVeg) sera reacted strongly with Dsc1 and Dsc3. Mammalian ELISAs were highly specific and more sensitive than baculoprotein ELISAs or the cDNA transfection method. Several Dsc-positive sera, particularly PH sera, showed no reactivity with Dsgs. The reactivity of PNP serum and PVeg serum with Dscs was not abolished by pre-absorption with Dsg RPs. The results of these novel ELISAs indicated that IgG anti-Dsc autoantibodies were frequently detected and potentially pathogenic in nonclassical pemphigus.

Immune cellular regulation on autoantibody production in pemphigus

Pemphigus is an autoantibody-mediated blistering disease in the skin and mucous membranes. The autoantibodies primarily target desmoglein (Dsg)1 or/and Dsg3, transmembrane glycoproteins of skin epidermal cells, leading to loss of desmosome adhesion and acantholysis through signaling dependent and independent pathways. Thus, the pemphigus autoantibodies themselves and immune processes, particularly cellular regulation of antibody production, remain as interesting topics in probing pemphigus pathogenesis. In this review, we focus on current advances regarding how the pemphigus antibody production is highly regulated by the key immune effectors including T cells, B cells and their secreted cytokines. Specifically targeting these immune effectors involved in the pemphigus autoantibody production should provide better therapeutic options for disease treatment of pemphigus.

Intravenous immunoglobulin G in the treatment of autoimmune bullous disease.

Intravenous immunoglobulin G in the treatment of autoimmune bullous disease.

Two decades of using the combination of tetracycline derivatives and niacinamide as steroid-sparing agents in the management of pemphigus: Defining a niche for these low toxicity agents

The twin goals of long-term disease control and minimizing toxicities related to immunosuppression necessitate efforts to find effective steroid-sparing agents in the management of patients with autoimmune bullous diseases. Pemphigus especially requires a long view, because the disease can persist throughout a patient's lifetime, yet few clinical trial reports exist to guide the practitioner. We review the response of pemphigus patients to tetracycline, doxycycline, or minocycline plus niacinamide (TCN/NAM) as steroid-sparing therapy and to determine the effects of TCN/NAM on autoantibody levels during the long-term treatment of pemphigus. This was a retrospective chart review in a private medical dermatology practice setting of all pemphigus patients treated between 1993 and 2013. Clinical responses to TCN/NAM therapy after initial high-dose steroid induction therapy and pemphigus antibody levels were recorded over the course of disease flares and treatment cycles along with any related side effects. Anti-desmoglein 1 and 3 titers were compared in a subset of patients over time, and a statistical analysis was performed to correlate the clinical response with antibody levels. Fifty-one pemphigus patients (43 with pemphigus vulgaris, 7 with pemphigus foliaceous, and 1 with pemphigus erythematosus) received at least 3 months of TCN/NAM, and 16 patients with pemphigus vulgaris had 1 set of pemphigus antibody titers correlating to a baseline/flare and clinical remission. TCN/NAM was associated with disease control in 43 of 51 patients, with a duration of response ranging from 1 to 13 years (mean, 3.14 ± 2.97 years). Thirteen of 51 patients needed no additional treatment for complete disease control, while 33 of 51 needed intermittent topical clobetasol or short courses of oral steroids for long-term management. There were 5 nonresponders. Antidesmoglein titers trended lower in TCN/NAM responders, but only desmoglein 3 approached statistical significance (anti-desmoglein 1, P= .21; anti-desmoglein 3, P= .02). This is a retrospective analysis from a single practice. A lack of serial autoantibody titers limited statistical analyses. TCN/NAM may be useful as a steroid-sparing therapy for pemphigus.

Relationship of regulatory B cells with pathogenic antibodies in pemphigus

Objective To explore the mechanisms underlying the mediating effect of regulatory B (Breg)cells in the pathogenesis of pemphigus.Methods Peripheral blood specimens were collected from 48 patients with pemphigus at different degrees of severity and 20 healthy controls.Flow cytometry was conducted to analyze the frequency of Breg(CD19 +CD24hiCD38hi)cells in peripheral CD19+ B cells,enzyme linked immunosorbent assay(ELISA)to determine the titer and subtypes of anti-desmoglein(Dsg)1 and 3 antibodies in sera from these subjects.The relationship of anti-Dsg 1 and 3 antibodies with the frequency of Breg cells was assessed by Spearman's rank correlation test.Results Significant differences were observed in the proportion of Breg cells in CD19+ B cells between patients with pemphigus and healthy controls(11.54％ ± 0.97％ vs.8.19％ ± 0.85％,P =0.04),as well as between patients with acute mild pemphigus and those with moderate and severe pemphigus(5.17％ ± 2.14％ vs.11.38％ ± 5.30％ and 11.17％ ± 5.31％,P =0.042,0.046,respectively).The frequency of Breg cells was positively correlated with the absorbance value for anti-Dsg1 antibodies of IgG4 subclass and IgG4/IgG1 ratio(r =0.527,0.565,respectively,both P ＜ 0.01).Conclusions Breg cells are mainly associated with the production of antibodies in and disease severity of pemphigus,while the actual mechanism of action remains unknown. Key words: Pemphigus; B lymphocytes; Antibodies

Enrichment of total serum IgG4 in patients with pemphigus

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are potentially fatal blistering diseases caused by autoantibodies targeting desmoglein (Dsg) adhesion proteins. Previous studies have shown an IgG4 > IgG1 predominance of anti-Dsg antibodies in pemphigus; however, no studies have examined total serum IgG4 levels in pemphigus. IgG4 is induced by chronic antigen stimulation, which could occur with persistent skin blistering and potentially elevate the total serum IgG4 relative to other IgG subclasses in patients with pemphigus. The primary aim of the study was to quantitate total and Dsg-specific IgG subclasses in patients with pemphigus. IgG subclasses and Dsg-specific IgG1 and IgG4 were quantitated in patients with PV and PF, and in sera from age-matched controls using a subclass enzyme-linked immunosorbent assay. The effectiveness of IgG4 depletion in blocking IgG pathogenicity in PV was determined using a keratinocyte dissociation assay. Dsg-specific antibodies comprised a median of 7·1% and 4·2% of total IgG4 in patients with PV and PF, respectively, with eightfold and fourfold enrichment in IgG4 vs. IgG1. Total serum IgG4, but not other IgG subclasses, was enriched in patients with PV and PF compared with age-matched controls (P = 0·004 and P = 0·005, respectively). IgG4 depletion of PV sera reduced pathogenicity in a keratinocyte dissociation assay and showed that affinity-purified IgG4 is more pathogenic than other serum IgG fractions. Dsg-specific autoantibodies are significantly enriched in IgG4, which may explain the enrichment of total serum IgG4 in some patients with pemphigus. By preferentially targeting autoimmune rather than beneficial immune antibodies, IgG4-targeted therapies may offer safer treatment options for pemphigus.

Epitope Spreading Is Rarely Found in Pemphigus Vulgaris by Large-Scale Longitudinal Study Using Desmoglein 2–Based Swapped Molecules

Epitope spreading is involved in inducing and maintaining self-reactivity. Epitope spreading in pemphigus vulgaris (PV), caused by IgG autoantibodies to desmoglein 3 (Dsg3) and Dsg1, was previously analyzed using Dsg3/Dsg1 extracellular domain-swapped molecules. However, precise identification of the responsible epitopes in each molecule by using only this method was problematic. In this study, we studied epitope spreading in PV by a novel immunoprecipitation-immunoblot method using Dsg3 (or Dsg1)/Dsg2 domain-swapped molecules, which overcomes the problems associated with the previous approaches. We analyzed the antigenic epitopes recognized by 212 sera collected from 53 PV patients at multiple disease stages. The major epitopes were present at the N-terminal region of Dsgs and were unchanged over the course of the disease in both anti-Dsg3 mucosal dominant-type PV and anti-Dsg3/Dsg1 mucocutaneous-type PV. These N-terminal epitopes were calcium dependent. Circulating antibodies in paraneoplastic pemphigus and pemphigus herpetiformis had unique epitope distributions, although the Dsg N-termini still contained the major epitopes. These results suggest that, after onset, intramolecular and intermolecular epitope spreading among extracellular domains on Dsg3 and Dsg1 is rare in PV and has no correlation with disease course.

Pathogenic activity of circulating anti-desmoglein-3 autoantibodies isolated from pemphigus vulgaris patients

IntroductionThere are scarce data on immunochemical properties of pemphigus antibodies detected in clinical remission in pemphigus vulgaris (PV) patients. The aim of the study was to compare biological activity of anti-Dsg3 autoantibodies purified from the sera of PV patients in active stage and in clinical remission.Material and methodsThe effect of purified antibodies on expression of procaspase-3, Bax, Bcl-2, uPAR, IL-1β, IL-6, and TNF-α mRNAs in the HaCaT keratinocytes was evaluated by Western blot and RT-PCR method.ResultsIncubation of HaCaT cells with anti-Dsg-3 autoantibodies caused their binding to cell membranes surfaces. Anti-Dsg3 autoantibodies isolated from the patients in active stage and clinical remission showed proapoptotic effect, caused enhanced expression of analyzed proinflammatory cytokines’ mRNAs and uPAR mRNA.ConclusionsOur data revealed similar pathogenic activity of anti Dsg-3 autoantibodies isolated from active and clinical remission PV patients.

Effect of intravenous immunoglobulin with or without cytotoxic drugs on pemphigus intercellular antibodies

Intravenous immunoglobulin (IVIg)--a relatively new approach to treat pemphigus--lowers serum levels of pemphigus antibodies; however, the optimal way to use this agent is unknown. We sought to examine whether coadministration of a cytotoxic drug to patients with pemphigus improves the ability of IVIg to decrease serum levels of intercellular (IC) antibodies. In this retrospective study, we analyzed changes in IC antibody levels in 20 patients with pemphigus who were treated with 24 courses of IVIg administered alone (n = 10) or with a cytotoxic drug (n = 14). Each course of IVIg consisted of 400 mg/kg daily of immunoglobulin given over 5 days every other week; this cycle was repeated 3 to 4 times. Serum levels of IC antibodies were measured at baseline, before treatment, and 1 week and 1 month after the last IVIg cycle. One week after the last IVIg cycle IC antibodies decreased by an average of 77% in the group treated with IVIg and cytotoxic drug compared with 48% in the group treated with IVIg alone (P = .54), and by 90% versus 43% 1 month later (P = .03). A larger sample size is suggested for future studies. These observations confirm that IVIg can rapidly lower serum levels of autoantibodies in patients with pemphigus and its ability to do so is improved by the coadministration of a cytotoxic drug. These findings imply that the clinical effectiveness of IVIg in treating pemphigus, and possibly other autoantibody-mediated diseases, may be improved by the concurrent administration of a cytotoxic drug.

High-dose pemphigus antibodies against linear epitopes of desmoglein 3 (Dsg3) can induce acantholysis and depletion of Dsg3 from keratinocytes

We have previously demonstrated that serum autoantibodies of patients with pemphigus vulgaris (PV) may affect desmoglein 3 (Dsg3)-mediated adhesion by decreasing its half-life and inducing Dsg3 cleavage. Here we sought to gain more insights into the role of Dsg3-targetting IgG in acantholysis. To do so, alterations of keratinocyte morphology and cell–cell adhesion strength were investigated in the presence of PV serum, PV IgG, and IgG purified from PV patients’ sera against linear epitopes of Dsg3 (anti-Dsg3-L IgG). Changes in Dsg3 protein levels were assessed by Western blotting. Results showed that both PV serum and PV IgG were able to induce acantholysis and decrease the total amount of Dsg3 in cell lysates. Polyclonal anti-Dsg3-L IgG displayed Dsg3-depleting activity solely when used at 1 μg/ml, i.e. under non-physiologic conditions. Furthermore, cell–cell detachment induced by PV IgG and anti-Dsg3-L IgG seemed to precede the loss of Dsg3 from keratinocytes, suggesting that depletion/degradation of Dsg3 represents a late event in acantholysis. Collectively, the data presented here demonstrate that PV IgG recognizing non-conformational epitopes of Dsg3 are pathogenic when administered on doses largely exceeding those found in PV sera.