IgG against extracellular subdomains of desmoglein 3 relates to clinical phenotype of pemphigus vulgaris

Abstract:  Pemphigus vulgaris (PV) is associated with autoantibodies against desmoglein (Dsg) 3 inducing epidermal loss of adhesion. The major pathogenic epitopes of Dsg3 are presumably dependent of their conformation. The aim of this study was to characterize the IgG reactivity of sera from a cohort of clinically well-characterized PV patients against presumably non-conformational subdomains of the Dsg3 ectodomain including recently described NH₂-terminal immunodominant epitopes. By ELISA, IgG reactivity against distinct subdomains of Dsg3 was related to disease activity and the clinical phenotype of PV patients. Our findings suggest that (i) autoantibody from PV sera react with non-conformational epitopes of Dsg3; (ii) IgG reactivity against the NH₂-terminus and the extracellular domains (EC) 2-4 of Dsg3 was associated with active PV, while IgG titres were not strictly correlated with disease activity and (iii) IgG reactivity against the EC1-4 was associated with mucosal dominant PV and was decreased in cutaneous dominant PV. The findings may help to define more refined serological disease markers of PV.     

A study of desmoglein 1 autoantibodies in pemphigus vulgaris: racial differences in frequency and the association with a more severe phenotype

BACKGROUND: Pemphigus vulgaris (PV) is characterized by pathogenic autoantibodies to desmoglein (Dsg) 3, but additional antibodies to Dsg1, the pemphigus foliaceus antigen, are detectable in some cases. OBJECTIVES: To investigate the clinical significance of the presence of both Dsg 1 and 3 antibodies. METHODS: In 79 subjects with PV, enzyme-linked immunosorbent assays were used to detect IgG autoantibodies reactive with the ectodomain of Dsg1 and Dsg3. RESULTS: There was a clear association between the clinical phenotype and the Dsg antibody profile. All subjects had Dsg3 autoantibodies and 61% had coexisting Dsg1 antibodies (Dsg3+/Dsg1+). PV limited entirely to the mucosal surfaces was seen only in Dsg3+/Dsg1- patients, while additional Dsg1 antibodies (Dsg3+/Dsg1+) predicted cutaneous in addition to mucosal involvement. Although minor cutaneous involvement was observed in most Dsg3+/Dsg1- patients, severe cutaneous involvement was seen only in Dsg3+/Dsg1+ patients. Dsg1 antibodies were detectable early in the course of disease and their appearance did not relate to the use of systemic therapy. The proportion of Dsg1+ patients was higher in those of Indian origin compared with white northern Europeans (P < 0.05). CONCLUSIONS: These data suggest that the presence of Dsg1 antibodies is predictive of a potentially more severe disease and that genetic factors may determine the Dsg antibody profile.     

IgG, IgA and IgE autoantibodies against the ectodomain of desmoglein 3 in active pemphigus vulgaris

BACKGROUND: IgG autoantibodies against desmoglein (Dsg) 3 play a key part in the pathogenesis of pemphigus vulgaris (PV), the most severe autoimmune bullous disorder. OBJECTIVES: To determine whether immunoglobulin isotypes other than IgG are detectable in the sera of patients with PV and whether a particular immunoglobulin subtype is associated with a distinct clinical phenotype of PV. METHODS: Sera from 41 patients with acute-onset, chronic active, and remittent PV disease with mucosal and cutaneous lesions were assayed against a baculovirus-expressed Dsg3 protein by immunoblot analysis. RESULTS: In acute-onset PV, Dsg3-reactive IgG1 was detected in nine of 15 (60%), IgG4 in 14 of 15 (93%), IgA in nine of 15 (60%) and IgE in two of 15 (13%) sera. In chronic active PV, Dsg3-reactive IgG1 was detected in 11 of 18 (61%), IgG4 in 16 of 18 (89%), IgA in 13 of 18 (72%) and IgE in two of 18 (11%) sera. In contrast, sera from patients with remittent PV disease contained only Dsg3-reactive IgG1 in six of eight (75%) and IgG4 in four of eight (50%) cases, but not Dsg3-reactive IgA or IgE. CONCLUSIONS: In extension of previous findings, our study demonstrates that, in addition to IgG autoantibodies, IgA and occasionally IgE autoantibodies reactive with Dsg3 are present in acute and chronic active PV. The detection of Dsg3-reactive autoantibodies of the IgG4, IgA and IgE subclasses in active PV provides additional evidence that PV is a T-helper 2-regulated autoimmune disorder.     

Monitoring disease activity in pemphigus with enzyme-linked immunosorbent assay using recombinant desmogleins 1 and 3

BACKGROUND: Pemphigus is an antidesmoglein (Dsg) autoimmune disease that is divided into two major subtypes: pemphigus foliaceus (PF) and pemphigus vulgaris (PV). We previously developed enzyme-linked immunosorbent assays (ELISAs) using recombinant Dsg1 and Dsg3 to detect IgG autoantibodies in patients with pemphigus. The protocol for the ELISAs was optimized for serological diagnosis, but under the conditions used, these assays were not particularly useful for monitoring disease activity in certain patients. That is, the sera from some patients with high-titre antibodies continued to show high index values in the ELISA after clinical improvement. OBJECTIVES: In the study reported here, we modified the ELISA protocol to obtain 'true' index values that exhibit a better correlation with disease activity. METHODS: We tested two cases of pemphigus foliaceus (PF) and four cases of pemphigus vulgaris (PV), each with ELISA index values greater than 150 for Dsg1 or Dsg3. We ran an ELISA with sera from these patients serially diluted from 1 : 100 to 1 : 12,800. We then performed ELISA with a series of PV No. 1 sera diluted to 1 : 800 and PV No. 2-4 and PF No. 1-2 sera diluted to 1 : 1600, after which we plotted the ELISA index values against the time course of disease activity. RESULTS: In each of these cases, there was no apparent decline, over the course of the disease activity, in the ELISA index values at a serum dilution of 1 : 100, probably because the antigen-antibody reaction was saturated at that dilution. After running an ELISA with sera serially diluted from 1 : 100 to 1 : 12,800 we found that a linear dose-dependency between the dilution value and the index value was only observed when sera were diluted to 1 : 800 or more in one case (PV No.1) and to 1 : 1600 or more in the other five cases (PV No. 2-4, PF No. 1-2). After performing ELISA with these series as outlined above we plotted the ELISA index values against the time course of disease activity and found that the index values obtained from these appropriately diluted sera fluctuated in parallel with disease activity, and declined with clinical improvement. CONCLUSIONS: These findings indicate that when appropriate dilutions are used in Dsg1 and Dsg3 ELISA, these assays can provide useful serological information for assessing disease activity in PF and PV.     

The transition of pemphigus vulgaris into pemphigus foliaceus: a reflection of changing desmoglein 1 and 3 autoantibody levels in pemphigus vulgaris

The transition of pemphigus vulgaris (PV) into pemphigus foliaceus (PF) is rare and the immunological changes underlying this event are not well understood. We report a 44-year-old woman who presented with oral and cutaneous erosions typical of PV. Over a 9-year period, the clinical features evolved into those of PF. To examine whether quantitative changes in desmoglein (Dsg) antibodies were associated with this transition, Dsg1 and Dsg3 antibody levels were measured by enzyme-linked immunosorbent assay in 82 sequential serum samples collected over this period. At presentation, when the phenotype was PV with oral and cutaneous erosions, antibodies to both Dsg1 and Dsg3 were detected. The disappearance of oral involvement was associated with a decline in Dsg3 antibodies, which are now undetectable, while the development of more severe skin involvement was associated with rising Dsg1 antibody levels. These data strongly suggest that the change in clinical features is a reflection of qualitative and quantitative changes in antibody profile. It is not known whether the transition to PF is permanent or whether disease relapses in the future may be associated with the re-emergence of Dsg3 antibodies, oral ulceration and a PV phenotype.     

The clinical transition between pemphigus foliaceus and pemphigus vulgaris correlates well with the changes in autoantibody profile assessed by an enzyme-linked immunosorbent assay

BACKGROUND: There are a number of reports of pemphigus with clinical shifting between pemphigus foliaceus (PF) and pemphigus vulgaris (PV). On the other hand, a novel enzyme-linked immunosorbent assay (ELISA) against recombinant baculoproteins of desmoglein 1 (Dsg1) (PF antigen) and Dsg3 (PV antigen) has been established and found to be extremely sensitive and specific. OBJECTIVES: To characterize the change in the antibody profiles in a series of pemphigus cases with mixed features of PF and PV by various methods, including the novel ELISA. Patients/methods Sera were obtained from eight cases undergoing a shift between PF and PV and three cases of coexistent PF and PV. The autoantigens were analysed by ELISA, as well as by immunofluorescence using normal human skin sections and immunoblotting using normal human epidermal extracts. RESULTS: The results of the ELISA, immunofluorescence and immunoblotting studies showed that the transition between PF and PV correlates well with the changes of autoantibodies against either Dsg1 or Dsg3. CONCLUSIONS: The clinical phenotype at each stage is defined by the anti-Dsg antibody profile in the serum of these pemphigus patients showing mixed features of PF and PV. In addition, ELISA using recombinant baculoproteins was particularly useful in distinguishing PF and PV.     

Evaluating efficacy of plasmapheresis for patients with pemphigus using desmoglein enzyme-linked immunosorbent assay

BACKGROUND: Pemphigus is an autoimmune bullous disease caused by circulating IgG autoantibodies against cell-cell adhesion molecules between keratinocytes: desmoglein (Dsg) 3 and Dsg1. Plasmapheresis is often used to treat severe cases of pemphigus. Enzyme-linked immunosorbent assays (ELISAs) against recombinant Dsg3 and Dsg1 have recently become available, allowing us to quantify IgG autoantibodies against Dsg3 and Dsg1. OBJECTIVES: Using ELISA against recombinant Dsg3 and Dsg1, to evaluate the efficacy of plasmapheresis in pemphigus. METHODS: Sera obtained from 10 patients with pemphigus vulgaris and one with pemphigus foliaceus following a total of 16 cycles of centrifugal plasmapheresis and 12 effluents from the plasmapheresis were subjected to ELISA against Dsgs. The percentage of IgG autoantibodies removed was calculated using two different formulae: one used serum titres before and immediately after plasmapheresis and the other used the absolute amounts of IgG autoantibodies in the effluents. The percentage fall of anti-Dsg antibody level was also calculated using the serum titres 1 day after plasmapheresis. RESULTS: Using serum titres immediately after plasmapheresis, there was a mean fall per treatment in anti-Dsg 3 antibody level of 43.0% (n = 12) and in anti-Dsg1 antibody level of 48.4% (n = 7). By contrast, calculated from the effluents, on average one treatment removed only 14.6% of anti-Dsg3 antibodies (n = 12) and 16.4% of anti-Dsg1 antibodies (n = 7). This should reflect the correct percentage as it is based on the absolute amounts of IgG autoantibodies removed. Using serum titres 1 day after plasmapheresis, there was a mean fall per treatment in anti-Dsg 3 antibody level of 12.9% (n = 2) and in anti-Dsg1 antibody level of 8.4% (n = 4). The percentage of IgG autoantibodies removed 1 day after plasmapheresis was lower than that found to be removed immediately after plasmapheresis (n = 6). CONCLUSIONS: One centrifugal plasmapheresis procedure eliminates about 15% of the IgG autoantibodies from the whole body. The percentage fall of anti-Dsg IgG antibody level differed depending on when the serum samples were obtained after plasmapheresis. The change in the percentage fall of anti-Dsg antibody level within 1 day after plasmapheresis is thought to be attributable to the passive diffusion of the IgG autoantibodies from the extravascular space to the intravascular space. Therefore, removal of IgG autoantibodies calculated using serum titres only should be evaluated carefully considering the equilibration of the IgG autoantibodies between the different body spaces.     

Serum and salivary desmoglein 1 and 3 enzyme‐linked immunosorbent assay in pemphigus vulgaris: correlation with phenotype and severity

Background To the best of our knowledge there is only one report about salivary desmoglein (Dsg) 1 and 3 enzyme‐linked immunosorbent assay (ELISA) in pemphigus vulgaris (PV), whereas several studies have been performed on serum. Aims To find the sensitivity of serum and salivary anti‐Dsg1 and 3 antibodies in the diagnosis of PV, and to determine the relationship between disease severity and phenotype with antibody levels. Methods Fifty new patients with PV were included in this study. The diagnosis of PV was confirmed by histopathology and direct immunofluorescence. Demographical data, disease severity and phenotypes were recorded on questionnaire sheets. Dsg1 and Dsg3 ELISA were performed on serum and salivary samples of patients and controls. Results Thirty‐seven patients had mucocutaneous phenotype; whereas mucosal dominant and cutaneous dominant phenotypes were seen in 11 and 2 patients respectively. The sensitivities of serum anti‐Dsg3 and anti‐Dsg1 were 94% and 72% respectively. The sensitivities of salivary anti‐Dsg3 and anti‐Dsg1 antibodies were accordingly 94% and 70%. Compared with mucosal phenotype, serum and salivary anti‐Dsg1 antibodies were significantly higher in the patients with mucocutaneous phenotype. Serum Dsg1 antibodies were related with cutaneous and serum Dsg3 antibodies with mucosal severity scores. Salivary Dsg1 antibodies were significantly correlated with mucosal severity (P = 0.00); however there was no correlation between this antibody and cutaneous severity (P = 0.07). Salivary Dsg3 antibodies were not correlated with mucosal severity (P = 0.16). Conclusion Saliva Dsg ELISA could be used for diagnosis of PV. Salivary Dsg1 antibodies had a significant correlation with mucosal severity.     

The detection of IgG and IgA autoantibodies to desmocollins 1-3 by enzyme-linked immunosorbent assays using baculovirus-expressed proteins, in atypical pemphigus but not in typical pemphigus

BACKGROUND: We have shown previously that human desmocollin (Dsc) 1 is recognized by IgA autoantibodies of subcorneal pustular dermatosis (SPD) type IgA pemphigus. However, the presence of IgG anti-Dsc autoantibodies is still controversial, and antibodies to Dsc2 and Dsc3 have not been clearly identified. OBJECTIVES: To investigate this by producing recombinant proteins consisting of the entire extracellular domains of human Dsc1, 2 and 3 in baculovirus, and to use them to establish an enzyme-linked immunosorbent assay (ELISA). METHODS: By this ELISA, we examined in total 165 cases of various types of autoimmune bullous diseases, as well as 23 normal controls. RESULTS: None of 45 sera of classical pemphigus showed either IgG or IgA antibodies to any Dsc. In contrast, one atypical pemphigus serum showed both IgG and IgA antibodies to Dsc1, which were adsorbed by incubation with Dsc1 baculoprotein. Furthermore, this ELISA detected both IgA and IgG anti-Dsc3 antibodies in one atypical case, and IgA antibodies to both Dsc2 and Dsc3 in another. This reactivity was confirmed by positive IgA immunofluorescence with Dsc2 and Dsc3 expressed on COS-7 cells. These results show that both IgG and IgA autoantibodies against all of Dsc1-3 are present in the sera of particular cases of nonclassical pemphigus, except for IgG antibodies to Dsc2, but that they are not detected in classical pemphigus. Unexpectedly, although IgA antibodies of all of eight SPD type IgA pemphigus sera reacted with Dsc1 expressed on COS-7 cells, only one serum was positive in Dsc1 ELISA for IgA. CONCLUSIONS: This result indicates either that Dscs expressed by baculovirus may not adopt the correct conformation or that Dscs may need association with other molecules to express all the epitopes for autoantibodies.     

Two cases of erosive oral lichen planus with autoantibodies to desmoglein 3

Oral lichen planus (OLP) is a chronic inflammatory disorder of the oral mucosa of unknown etiology. Clinically, the erosive type of OLP (erosive OLP) can show features similar to those of pemphigus vulgaris (PV), an autoimmune blistering disorder in which desmoglein (Dsg)3 is targeted. In addition to clinical and histopathological findings, immunological studies, including direct immunofluorescence (IF), indirect IF and enzyme‐linked immunosorbent assay (ELISA) that detect autoantibodies to Dsg3, are helpful in differentiating erosive OLP from PV. Here, we show two cases of erosive OLP with autoantibodies to Dsg3. Patient 1 was a 68‐year‐old woman with chronic erosions of the oral mucosa, in which elevated levels of immunoglobulin (Ig)G autoantibodies to Dsg1 and Dsg3 were detected by ELISA. Patient 2 was an 85‐year‐old woman with white striae with erosions on the lateral sides of the buccal mucosa with elevated levels of IgG autoantibodies to Dsg3 detected by ELISA. Histopathological findings from both cases showed lichenoid dermatitis, and both direct and indirect IF showed no tissue‐bound IgG autoantibodies. From these findings, the diagnosis of erosive OLP was made. Immunological assays revealed both cases to have IgG‐directing calcium‐independent linear epitopes on Dsg3, which are suggestive of non‐pathogenic autoantibodies. In addition, autoantibodies to Dsg3 in patient 2 reacted with a prosequence‐possessing precursor form of Dsg3 but not with the mature form of the molecule. The present study suggests that erosive OLP may develop anti‐Dsg3 autoantibodies, which should be carefully assessed.     

Usefulness of enzyme-linked immunosorbent assay using recombinant desmogleins 1 and 3 for serodiagnosis of pemphigus

Pemphigus is an autoimmune blistering disease with two major subtypes, pemphigus vulgaris (PV) and pemphigus foliaceus (PF). Patients with pemphigus have circulating antidesmoglein (Dsg)1 and/or anti-Dsg3 IgG autoantibodies. We have previously developed enzyme-linked immunosorbent assays (ELISAs) using recombinant Dsg1 and Dsg3 expressed by baculovirus as a diagnostic tool for pemphigus. The purpose of this study was to evaluate the practical application of these ELISAs for clinical use with a large number of serum samples. We used 81 PV sera, 48 PF sera, 114 bullous pemphigoid (BP) sera, 124 collagen disease sera, nine sera of other non-pemphigus bullous diseases and 179 normal control sera. A cut-off value was determined by receiver-operating-characteristic plots. Forty-seven of 48 PF sera (97.9%) were positive in the Dsg1 ELISA and 79 of 81 PV sera (97.5%) were positive in the Dsg3 ELISA, while only two (1. 1%) and four (2.2%) of 179 normal sera were positive in Dsg1 and Dsg3 ELISAs, respectively. However, some disease control sera of BP and collagen diseases exceeded the cut-off value. Introduction of a grey zone helped to decrease the number of these false-positive sera. Furthermore, in three patients studied, the respective Dsg1 and Dsg3 ELISA scores showed parallel fluctuation with the disease activity along the time course. We conclude that Dsg1 and Dsg3 ELISAs provide a simple, sensitive and highly specific assay for the diagnosis of patients with PV and PF and that these ELISAs may be a valuable tool to monitor the disease activity. We also propose diagnostic criteria for pemphigus based on ELISA reactivity: if a serum is positive against Dsg3 it indicates a diagnosis of PV, regardless of reactivity against Dsg1; if a serum is negative for Dsg3 and positive for Dsg1, it indicates a diagnosis of PF.     

IgG/IgA pemphigus with IgG and IgA antidesmoglein 1 antibodies detected by enzyme-linked immunosorbent assay

Pemphigus is an autoimmune mucocutaneous bullous disease characterized by autoantibodies against the cell surfaces of epidermal keratinocytes. Six cases with deposition of both IgG and IgA on keratinocyte cell surfaces have been reported in the recent literature. We provisionally termed these cases IgG/IgA pemphigus. We describe a 42-year-old Japanese woman with clinical and histopathological features resembling herpetiform pemphigus who demonstrated in vivo bound and circulating anticell surface autoantibodies of both IgG and IgA classes on immunofluorescence examination. Enzyme-linked immunosorbent assay using baculovirus-expressed recombinant desmoglein (Dsg) 1 and Dsg 3 showed that both IgG and IgA antibodies reacted with Dsg1. The reactivity was completely adsorbed with preincubation of serum with Dsg1 baculoprotein, further confirming the exclusive reactivity of both IgG and IgA antibodies with Dsg1. This is the second case of IgG/IgA pemphigus in which the human target antigens for both IgG and IgA antibodies have been unequivocally identified. This study provides further evidence that IgG/IgA pemphigus is a distinct disease entity.     

Evidence of an association between desmoglein 3 haplotypes and pemphigus vulgaris

BACKGROUND: Pemphigus vulgaris (PV, OMIM 169610) is a severe blistering disorder of the skin and mucous membranes, caused by the production of autoantibodies directed against the epithelial adhesive protein desmoglein 3. Although an association between PV and HLA class II alleles has been established, the genetic factors predisposing to the disease remain poorly understood, the rarity of PV hampering the recruitment of substantial patient cohorts. OBJECTIVES: To investigate DSG3 as a candidate PV susceptibility gene. METHODS: We examined five DSG3 single nucleotide polymorphisms (rs8085532, rs3911655, rs3848485, rs3794925 and rs1466379) in two case-control datasets respectively originating from the U.K. (62 PV patients, 154 controls) and northern India (28 patients, 98 controls). RESULTS: In the U.K. sample, we observed a significant association between PV and the DSG3*TCCTC haplotype (Fisher's exact test P = 0.002). A related haplotype (DSG3*TCCCC) was associated with PV in the Indian dataset (P = 0.002). We also found that all British and Indian patients bearing DSG3 risk haplotypes carried at least one copy of a PV-associated HLA allele. CONCLUSIONS: These results suggest that genetic variation of DSG3 may be an additive risk factor predisposing to PV and warrant further investigations of this gene.     

Cleavage of desmoglein 3 can explain its depletion from keratinocytes in pemphigus vulgaris

We have previously demonstrated that serum of patients with pemphigus vulgaris induces reduction of desmoglein 3 (Dsg3) half-life in keratinocytes (FEBS Lett 2006: 580: 3276). This phenomenon seems to occur as a consequence of the progressive depletion of Dsg3 from desmosomes. Here we reported that reduction of full-length Dsg3 may be due to its progressive cleavage, leading to the formation of two fragmentation products with apparent molecular masses of about 60 kDa (fragment 1) and 70 kDa (fragment 2), as revealed by Western blotting. Unexpectedly, analysis of fragmentation pattern suggested cleavage to occur intracellularly. Consistently, fragment 1 was shed and localized within the cytosol, as shown by living cell immunofluorescence microscopy. Total amounts of full-length plakoglobin and Dsg1 were apparently unchanged. Taken together, our findings provide evidence that proteolytic processing of Dsg3 can lead to depletion of Dsg3 from the cell.     

Atypical pemphigus with immunoglobulin G autoantibodies against desmoglein 3 and desmocollin 3

In patients with pemphigus vulgaris (PV), pathogenic immunoglobulin (Ig)G antibodies are most commonly directed against desmoglein 3 (Dsg3). It has recently been reported, however, that IgG anti‐desmocollin 3 (Dsc3) antibodies are detected in some cases of pemphigus with or without IgG anti‐Dsg3 antibodies. We present a case of pemphigus with IgG antibodies against Dsg3 and Dsc3. Subsequent studies showed that the cell surface distribution pattern of Dsc3 but not Dsg3 was altered, suggesting that suprabasal acantholytic blisters were induced by IgG anti‐Dsc3 antibodies rather than IgG anti‐Dsg3 antibodies. Our case suggests that anti‐Dsc3 antibodies may be pathogenic in cases positive for the dual cadherin autoantibodies.     

天疱疮患者病情与抗桥粒芯蛋白抗体水平的相关性研究

目的:研究天疱疮患者血清中抗桥粒芯蛋白(desmoglein,Dsg)1和抗Dsg3抗体水平与其皮肤、口腔黏膜损害严重程度的相关性,同时对间接免疫荧光(IIF)检测的天疱疮抗体滴度与治疗中使用皮质类固醇控制剂量的相关性进行分析。方法:采用酶联免疫吸附试验(ELISA)试剂盒测定55例天疱疮患者血清中抗Dsg1和抗Dsg3抗体水平。结果:抗Dsg1抗体水平与患者皮肤损害严重程度有显著相关性(P<0.01),抗Dsg3抗体水平与口腔黏膜损害严重程度有显著相关性(P<0.01)。天疱疮患者血清IIF滴度与抗Dsg1抗体水平相关(P<0.01),寻常型天疱疮患者IIF滴度与抗Dsg1和抗Dsg3抗体水平均有相关性(P分别<0.01和<0.05)。寻常型天疱疮患者皮质类固醇控制剂量与抗Dsg1抗体水平和IIF滴度显著相关(P<0.05)。结论:ELISA方法检测天疱疮患者抗Dsg1和抗Dsg3抗体对天疱疮的临床诊断、分型、衡量口腔黏膜和皮肤损害严重程度具有一定意义。     

Pemphigoid nodularis with IgA autoantibodies against the intracellular domain of desmoglein 1

Pemphigoid nodularis is a rare variant of bullous pemphigoid. We report a 49-year-old Japanese male with clinical and histopathological features of pemphigoid nodularis including circulating and in vivo-bound IgG antibasement membrane zone antibodies and IgA anti-intercellular antibodies. Although the precise molecular target of the IgG autoantibodies could not be determined, intriguingly, immunoblotting showed that the IgA in the patient's serum reacted with the intracellular domain of desmoglein 1, the target antigen in cases of pemphigus foliaceus. However, the IgA did not react with the extracellular domain of desmoglein 1 in sensitive enzyme-linked immunosorbent assay studies using a baculovirus system. These results suggest therefore that these IgA antibodies may possibly not be pathogenic. The mechanism for the production of different autoantibodies is unknown, but this case provides further illustration of the atypical skin immunoreactants often seen in this unusual subtype of bullous pemphigoid.     

Successful removal of pathogenic autoantibodies in pemphigus by immunoadsorption with a tryptophan-linked polyvinylalcohol adsorber

BACKGROUND: Autoantibodies against the glycoproteins desmogleins 1 and 3 which are components of the desmosomal adhesion complex have been shown to be responsible for the loss of epidermal adhesion characteristic of pemphigus. Elimination of these antibodies should clinically improve the pathology of this group of severe autoimmune blistering skin disorders. OBJECTIVES: To gather information about the efficacy of immunoadsorption in the reduction of pathogenic serum autoantibodies against desmogleins 1 and 3 and to evaluate the clinical benefit of immunoadsorption in the treatment of pemphigus. PATIENTS AND METHODS: Nine patients with pemphigus and detectable circulating desmoglein antibodies were included in this open trial. Two immunoadsorption treatments separated by a 48-h interval were performed per patient. Anti-desmoglein 1 and 3 antibodies in the patients' sera were monitored by enzyme-linked immunosorbent assay and indirect immunofluorescence before and following each immunoadsorption. In addition, the efficacy of the tryptophan-linked polyvinylalcohol adsorber in removing antidesmoglein antibodies was directly evaluated. RESULTS: IgG antibodies against desmogleins 1 and 3 were effectively eliminated from the patients' plasma upon passage through the adsorber and levels of serum autoantibodies were significantly reduced by immunoadsorption. A single immunoadsorption treatment led to a reduction of antidesmoglein autoantibodies of about 30%. Clinically, mucosal and cutaneous lesions improved allowing for a reduction of the systemic immunosuppressive treatment with glucocorticoids. CONCLUSIONS: Immunoadsorption with tryptophan-linked polyvinylalcohol adsorbers holds promise as a highly effective and safe adjuvant therapeutic regimen in pemphigus.