Subcorneal pustular dermatosis type of IgA pemphigus: demonstration of autoantibodies to desmocollin-1 and clinical review

Dapsone Use in Dermatology

Dapsone, initially synthesized for textile dyeing, gained recognition in the 1930s for its antibacterial properties, leading to its utilization in dermatology for leprosy and dermatitis herpetiformis. Despite US Food and Drug Administration (FDA) approval for these conditions, dapsone's off-label uses have expanded, making it a valuable option in various dermatologic conditions. This review seeks to highlight the common uses of dapsone in its FDA indications and off-label indications. Diseases in which dapsone is considered first-line therapy or adjunctive therapy are reviewed, with highlights from the resources included. An overview of dapsone's pharmacokinetics, pharmacodynamics, indications, dosages, and safety profile are also reviewed. Dapsone's versatility and safety profile make it a cost-effective treatment option in dermatology, particularly for patients with limited access to specialized medications. Ongoing clinical trials are also described exploring dapsone's efficacy in novel dermatologic uses. Dapsone has been a valuable adjunctive therapy across various dermatologic conditions for years and evidence for its use continues to expand.

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.

Anti-Desmocollin Autoantibodies in Autoimmune Blistering Diseases

The presence of anti-desmocollin (Dsc) antibodies is rarely described in autoimmune blistering diseases patients. Moreover, several clinical phenotypes of pemphigus may be associated with these antibodies. In this review we analyze clinicopathological, immunologic and outcome features of anti-Dsc autoimmune blistering diseases patients, to improve their diagnosis and management. We conducted a systematic search of PubMed and Embase (1990-present) for studies reporting cases of autoimmune blistering diseases with anti-Dsc antibodies. We classified the selected patients as patients with exclusively anti-Dsc autoantibodies, and patients with anti-Dsc and other autoantibodies. Of 93 cases with anti-Dsc autoantibodies included, 38 (41%) had exclusively these antibodies. Only 18% of patients presented with the typical clinicopathological phenotype of pemphigus vulgaris or pemphigus foliaceous. Mucosal involvement was seen in approximately half of the patients. Up to 18% of cases were associated with neoplasms. Acantholysis was described in 54% of cases with histopathological information. Treatments and outcomes vary in the different clinical phenotypes. The presence of anti-Dsc antibodies must be suspected mainly in those patients with either atypical pemphigus, in special with clinical pustules, or in cases showing intraepithelial or dermal neutrophilic/eosinophilic infiltrate on histological examination and dual pattern by direct immunofluorescence examination.

Intraepithelial autoimmune blistering dermatoses: Clinical features and diagnosis

Intraepithelial autoimmune blistering dermatoses are a rare group of skin disorders characterized by the intraepithelial disruption of intercellular connections through the action of autoantibodies. The first article in this continuing medical education series explores the background, epidemiology, clinical features, and diagnostic criteria of each of the major intraepithelial autoimmune blistering dermatoses, including pemphigus foliaceus, pemphigus erythematosus, pemphigus herpetiformis, fogo selvagem, pemphigus vulgaris, pemphigus vegetans, drug-induced pemphigus, IgA pemphigus, IgG/IgA pemphigus, and paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome.

Imatinib-induced IgA Pemphigus: Subcorneal Pustular Dermatosis Type

Imatinib mesylate, a tyrosine kinase inhibitor, is commonly used in the treatment of chronic myeloid leukemia. IgA pemphigus is a rare bullous dermatosis caused by IgA autoantibodies. Clinical manifestations include localized or generalized itchy blisters and pustules. Drug-induced IgA pemphigus has been rarely reported in the literature till date. Here, we report one such rare case caused by imatinib which responded poorly to oral prednisolone but showed excellent response to tablet dapsone.

IgA Pemphigus in a Child – a Case Report

IgA pemphigus (IGAP) is a rare autoimmune bullous disease characterized by IgA deposits on keratinocyte cell surfaces. The IGAP is classified into: 1) subcorneal pustular dermatosis (SPD) type, and 2) intraepidermal neutrophilic (IEN) IgA dermatosis type. So far, only 9 children with IGAP have been described in the literature, of whom only 3 with SPD type. We report a 3-year-old boy with SPD type of IGAP. Clinically, he presented with pruritic vesicles, pustules and erosions on the face, trunk, groin area, and extremities. Histopathology showed subcorneal pustules containing a few acantholytic cells. Direct immunofluorescence (DIF) test of Tzanck smear showed intercellular IgA deposits on the surface of the groups of epidermal cells. Oral dapsone and prednisone induced remission after two weeks; the treatment was discontinued 11 months later, and complete remission was achieved during 19 months without any treatment. Direct immunofluorescence of Tzanck smear is a simple, sensitive, rapid and non-aggressive test, very suitable for the diagnosis of IGAP in children.

Subcorneal Pustular Dermatosis: A Review of 30 Years of Progress

Subcorneal pustular dermatosis (SPD), also known as Sneddon-Wilkinson disease, is a rare, benign yet relapsing pustular dermatosis. Its incidence and prevalence have not been well studied. It characteristically presents as hypopyon pustules on the trunk and intertriginous areas of the body. SPD is similar to two other disease entities. Both SPD-type immunoglobulin (Ig)-A pemphigus and annular pustular psoriasis clinically and histologically present similarly to SPD. Immunologic studies separate SPD-type IgA pemphigus from SPD and pustular psoriasis. However, there is still an unclear designation as to whether SPD is its own entity distinct from pustular psoriasis, as the once thought characteristic histologic picture of psoriasis does not hold true for pustular psoriasis. SPD has been reported to occur in association with several neoplastic, immunologic, and inflammatory conditions. Dapsone remains the first-line treatment for SPD, although dapsone-resistant cases have been increasingly reported. Other therapies have been used singly or as adjunctive therapy with success, such as corticosteroids, immunosuppressive agents, tumor necrosis factor inhibitors, and ultraviolet light therapy. This article provides a review of the last 30 years of available literature, with a focus on successful treatment options and a suggestion for reappraisal of the classification of SPD.

Non-classical forms of pemphigus: pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus and IgG/IgA pemphigus

The pemphigus group comprises the autoimmune intraepidermal blistering diseases classically divided into two major types: pemphigus vulgaris and pemphigus foliaceous. Pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus and IgG/IgA pemphigus are rarer forms that present some clinical, histological and immunopathological characteristics that are different from the classical types. These are reviewed in this article. Future research may help definitively to locate the position of these forms in the pemphigus group, especially with regard to pemphigus herpetiformis and the IgG/ IgA pemphigus.

Double-blind placebo-controlled trial of dapsone in antihistamine refractory chronic idiopathic urticaria

BACKGROUND

Management of antihistamine refractory chronic idiopathic urticaria (CIU) has poorly defined therapeutic options.

OBJECTIVE

To evaluate the efficacy of dapsone (4,4'-diaminodiphenylsulfone) in antihistamine refractory CIU compared with placebo.

METHODS

Twenty-two patients with antihistamine refractory CIU were randomly assigned to 100 mg of dapsone daily or placebo for 6 weeks in a 14-week double-blind, placebo-controlled crossover trial. End points were measured from a daily diary that reflected the weekly hive score, the weekly itch score, and a visual analog scale (VAS) score. Secondary to a carryover effect, the first period results were analyzed as a parallel design that compared placebo with dapsone directly by using repeated-measures analysis.

RESULTS

After 6 weeks, the patients in the dapsone arm showed mean improvement over baseline in VAS (2.3 [95% CI, 0.6-4.1], P = .01), urticaria score (-3.5 [95% CI, -6.2 to -0.9], P = .01), and itch score (-4.8 [95% CI, -7.6 to -2.1], P = .001), whereas the placebo arm showed no improvement over baseline for VAS, urticaria, or itch scores. Dapsone showed greater improvement compared with placebo for itch (P = .047) and VAS (P = .04). Of the 22 patients, 3 showed complete resolution of hives and itch with dapsone, whereas 31% and 41% had ≥ 50% resolution of hives and itch, respectively. No serious adverse effects were observed with dapsone.

CONCLUSION

To our knowledge, this is the first double-blind, placebo controlled study of dapsone in CIU and indicates that dapsone has efficacy in patients with antihistamine refractory CIU.

Two Brazilian Cases of IgA Pemphigus

IgA pemphigus is a rare, neutrophilic, acantholytic skin disorder with approximately 70 cases described in the literature. We report two patients with the subcorneal pustular dermatosis (SPD) type of IgA pemphigus. Initially, both patients were misdiagnosed as subcorneal pustular dermatosis of Sneddon and Wilkinson. The correct diagnosis was only made after detecting intercellular IgA depositions in the epidermis by direct immunofluorescence. Immunoblotting (IB) of normal human epidermal extracts, performed on both sera, was negative for Dsg 1, Dsg 3, BP 230, BP 180, 210 kDa envoplakin, and 190 kDa periplakin. ELISA for desmogleins (Dsg 1 and Dsg 3) showed that neither of the cases had IgA antibodies to Dsg. The c-DNA transfection test for desmocollins (Dsc) revealed that the IgA antibodies of both patients reacted with desmocollin 1. This result supports the hypothesis that the autoantigen in SPD type IgA pemphigus is desmocollin 1.

Pemphigus foliaceus masquerading as IgA pemphigus and responding to dapsone

A 14-year-old male presented with seven years history of recurrent episodes of fluid filled, itchy and eroded lesions over the body not responding to oral corticosteroids and azathioprine. Dermatological examination revealed crusted plaques and erosions in a seborrheic distribution. Histopathology of skin lesions and direct immunofluorescence were characteristic of pemphigus foliaceus. He was treated with dexamethasone pulse therapy with inadequate response. However, relapsing skin lesions revealed a circinate arrangement with a predilection to trunk and flexures. In view of clinical features suggestive of IgA pemphigus, he was started on dapsone, to which he responded dramatically in four weeks. However, repeat biopsy continued to reveal features of pemphigus foliaceus and ELISA for anti-desmoglein 1 antibodies was positive.

[IgA pemphigus of the subcorneal pustular dermatosis type. Successful therapy with a combination of dapsone and acitretin]

IgA pemphigus of the subcorneal pustular dermatosis type is a rare autoimmune blistering disease in the pemphigus spectrum. Patients are clinically characterized by extensive erythemas that primarily affect intertriginous areas. The erythematous macules are covered with numerous vesicles and pustules with occasional hypopyon formation. Histopathology shows subcorneal acantholysis with clefting and numerous neutrophils within the blister as well as in the edematous papillary dermis. IgA autoantibodies bind in vivo to keratinocytes within the upper half of the epidermis. Desmocollin 1, the autoantigen of this disease, is a member of desmosomal cadherins and is only expressed on more differentiated keratinocytes. The demonstration of circulating autoantibodies against desmocollin 1 in routine diagnosis is challenging and requires indirect immunofluorescence staining of desmocollin 1 transfected COS7 cells. We report a patient with a severe course of the disease who only responded to combined therapy with dapsone and acitretin.

Current approaches to diagnostics and treatment of IgA pemphigus

The authors describe a case of a rare type of pemphigus - IgA pemphigus. They also discuss issues related to pathogenesis, classification, diagnostics and treatment of the disease.

IgA pemphigus--occurrence of anti-desmocollin 1 and anti-desmoglein 1 antibody reactivity in an individual patient

BACKGROUND

IgA pemphigus is a rare pustular autoimmune disease with exclusive IgA anti-keratinocyte cell surface antibody reactivity. Two subtypes have been discerned: in the subcorneal pustular dermatosis type, desmocollin 1 has been identified as a targeted autoantigen, while in few cases of the intraepidermal neutrophilic type, IgA anti-desmoglein 1 or IgA anti-desmoglein 3 reactivity has been demonstrated.

PATIENTS AND METHODS

A 48-year-old white male presented with generalized large confluent pustules. Skin pathology was assessed by histology and direct immunofluorescence analysis. IgG/IgA autoantibodies against desmoglein 1/3 and desmocollin 1 were measured by ELISA and indirect immunofluorescence using desmocollin 1 cDNA-transfected COS7 cells, respectively.

RESULTS

Histopathology revealed subcorneal pustules and direct immunofluorescence microscopy exclusively showed in vivo bound IgA with an intercellular pattern in the epidermis. Desmocollin 1 was identified as a target of IgA autoantibodies by indirect immunofluorescence microscopy utilizing desmocollin 1 cDNA-transfected COS7 cells. In addition, IgA anti-desmoglein 1 reactivity was demonstrated by ELISA. Neither IgA anti-desmoglein 3 nor IgG anti-desmoglein 1/3 autoantibodies were present.

CONCLUSIONS

Both desmocollin 1 and desmoglein 1 were autoantigens in this patient with IgA pemphigus and a distinct clinical presentation. To our knowledge, this is the first IgA pemphigus case with dual autoantibody reactivity.

Pénfigo

Pemphigus is an infrequent, organ-specific, autoimmune bullous disease, which affects the skin, mucous membranes and appendages. Histopathologically, it is characterized by acantholysis. Pemphigus has classically been divided into two major groups, pemphigus vulgaris and pemphigus foliaceus, with their respective clinical variants pemphigus vegetans and pemphigus erythematosus. In recent years, new variants of pemphigus have been described: paraneoplastic pemphigus, IgA pemphigus and pemphigus herpetiformis. This article reviews the epidemiology, etiopathogenesis, clinical symptoms, diagnosis, treatment and prognosis of pemphigus. Advances in molecular biology techniques have made it possible to more precisely identify the different antigens against which antibodies are directed, and to fine-tune ELISA diagnostic techniques. Treating pemphigus vulgaris and foliaceus with general steroids has modified their prognosis; it is estimated that mortality in recent decades is less than 10 %. Managing the clinical complications that appear during the evolution of the pemphigus has contributed to reducing morbidity and mortality.

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.

Immunolocalization of target autoantigens in IgA pemphigus

IgA pemphigus is a rare autoimmune bullous disease characterized by IgA deposition at keratinocyte cell surfaces. Clinically and histologically, IgA pemphigus is divided into two major subtypes: subcorneal pustular dermatosis (SPD) type and intraepidermal neutrophilic IgA dermatosis (IEN) type. Using cDNA transfection and living cell immunofluorescence, we previously showed that desmocollin 1, one of the desmosomal cadherins, is the autoantigen in SPD-type IgA pemphigus, but the autoantigen in IEN type is still unclear. In the present study we investigated antigen localization by postembedding immunoelectron microscopy. We examined three sera each of SPD-type and IEN-type IgA pemphigus. In SPD-type, gold particles were observed predominantly in the extracellular spaces between keratinocytes at desmosomes, although a few particles were observed in the intracellular domain at the desmosomal attachment plaques. In IEN type, the gold particles were observed mainly in the intercellular spaces in nondesmosomal areas. These results provide evidence that the IgA in the sera of SPD-type IgA pemphigus reacts with the extracellular domain of desmocollins. In contrast, the autoantigen for IEN type may in fact not be a component of desmosomes. IEN-type IgA pemphigus may be the first member of the pemphigus group of autoimmune bullous dermatoses that reacts with a nondesmosomal transmembranous protein.

Calcium-dependent conformation of desmoglein 1 is required for its cleavage by exfoliative toxin

In bullous impetigo, Staphylococcus aureus spreads under the stratum corneum of skin by elaboration of exfoliative toxin, which hydrolyzes only one peptide bond in a highly structured calcium-binding domain of desmoglein 1, resulting in loss of its function. We investigated the basis of this exquisite specificity. Exfoliative toxin cannot cleave desmoglein 1 pretreated at 56 degrees C or higher or at low or high pH, suggesting that the proper conformation of desmoglein 1 is critical for its cleavage. Because cleavage occurs in an area of desmoglein 1 stabilized by calcium, we determined if the conformation necessary for cleavage is calcium-dependent. Depletion of calcium from desmoglein 1 completely inhibited its cleavage by exfoliative toxin, even after calcium was added back. A change in conformation of desmoglein 1 by calcium depletion was shown, with immunofluorescence and enzyme-linked immunoassay, by loss of binding of PF sera, which recognize conformational epitopes. This change in conformation was confirmed by tryptophan fluorometry and circular dichroism, and was irreversible with repletion of calcium. These data suggest that the specificity of exfoliative toxin cleavage of desmoglein 1 resides not only in simple amino acid sequences but also in its calcium-dependent conformation.

Recent advances in the study of the pathophysiology of pemphigus

Recent rapid advances in the basic research into pemphigus have provided many insights into its pathophysiology. In particular, a recently developed enzyme-linked immunosorbent assay (ELISA) for desmogleins 1 and 3 (Dsg1 and Dsg3), antigens for pemphigus foliaceus (PF) and pemphigus vulgaris (PV), respectively, has led to great progress in the diagnosis and classification of pemphigus, as well as in understanding its pathomechanisms. Studies with the anti-Dsg1 and anti-Dsg3 antibodies have indicated that there are two types of PV, the mucosal dominant type and the mucocutaneous type. The same ELISA has identified the antigens in pemphigus herpetiformis. The autoantigens detected by this ELISA correlate well with the clinical features in pemphigus patients in showing the shift between PV and PF. In addition, the Dsg compensation theory proposed by Stanley and Amagai can reasonably explain the different depths of skin lesions and the different occurrences of skin and oral mucosal lesions between PV and PF. Furthermore, a complicated profile of autoantigens in paraneoplastic pemphigus (PNP) has been indicated in various biochemical studies, and IgG anti-Dsg1 and anti-Dsg3 antibodies have been detected in serum from all the PNP patients by the above ELISA. On the other hand, serum from subcorneal pustular dermatosis type IgA pemphigus patients have been shown to react with Dsc1, another type of desmosomal cadherin, by a novel cDNA transfection method. In addition, IgA anti-Dsg1 and anti-Dsg3 antibodies have been detected in a few patients with IgA pemphigus by an ELISA for IgA antibodies. Various autoimmune bullous diseases, including several types of pemphigus, are the only diseases in which the pathogenic role of circulating autoantibodies has been confirmed using the newborn mouse animal model. Therefore, studies of the pathophysiology of pemphigus are extremely important as a paradigm for research into various types of autoimmune diseases in other fields.

The pustular disorders

The pustular disorders constitute a subgroup of the vesiculobullous disorders defined by the presence of eosinophils or neutrophils with prominent accompanying intercellular edema or a canthelysis involving various levels of the epithelium. Herein, we describe the clinical and pathologic attributes of the subcorneal, infectious, neonatal, papulosquamous, drug-induced and miscellaneous pustular conditions.

Juvenile subcorneal pustular dermatosis: a case report

Subcorneal pustular dermatosis is a chronic, relapsing, pustular dermatosis that usually develops in elderly women. It is rarely seen in childhood and adolescence. The hallmark of the disease is formation of a subcorneal pustule detected on histopathologic examination. Herein we present a 13-year-old girl diagnosed with subcorneal pustular dermatosis based on the typical clinical and histologic findings. Direct and indirect immunofluorescence and serum protein electrophoresis had negative results. The patient partially recovered after 5 weeks of treatment consisting of oral dapsone and a topical steroid ointment.

Pemphigus herpetiformis with IgA and IgG antibodies to desmoglein 1 and IgG antibodies to desmocollin 3

We describe a case with clinical and histologic features of pemphigus herpetiformis associated with IgG and IgA anti-keratinocyte cell surface antibodies to desmoglein 1 (Dsg1) and exclusively IgG antibodies to desmocollin 3 (Dsc3). The clinical presentation was somewhat similar to IgA pemphigus; the main difference was the prevailing association with IgG antibodies to Dsg1. The presence of IgA anti-Dsg1 antibodies was confirmed by IgA enzyme-linked immunosorbent assay and IgG anti-Dsc3 antibodies were detected by a novel enzyme-linked immunosorbent assay with the use of baculovirus expressing recombinant Dscs for IgG and IgA. The reactivity of IgG antibodies with Dsc3 was confirmed by COS-7 cell cDNA transfection method using cDNA of human Dsc1 to Dsc3. We discuss the differentiation of pemphigus herpetiformis, associated with both IgG and IgA antibodies, from IgA pemphigus, particularly in regard to the autoimmune reaction with Dsgs and Dscs.

Clinical, histopathological and immunological distinction in two cases of IgA pemphigus

Two cases of IgA pemphigus, one of the subcorneal pustular dermatosis (SPD) type and one of the intraepidermal neutrophilic IgA dermatosis (IEN) type, are described. IgA anti-keratinocyte cell surface antibodies reacted only with the uppermost epidermis in the SPD type but with the entire epidermis in the IEN type. A cDNA transfection test for desmocollins (Dsc) revealed that IgA antibodies of the SPD type reacted with Dsc1, but the IEN type did not react with any of the Dsc isoforms (Dsc1-3). ELISA for desmoglein 1 (Dsg1) and Dsg3 showed that neither of the cases had antibodies to Dsg - of either the IgG or IgA subtype. These results confirm that the autoantigen in SPD-type IgA pemphigus is Dsc1, whereas the antigen in most cases of IEN-type IgA pemphigus is unknown.

Pemphigus--paradigm of autoantibody-mediated autoimmunity

Pemphigus encompasses a group of life-threatening autoimmune blistering diseases due to a loss of adhesion between keratinocytes, called acantholysis, which is caused by autoantibodies (AAb) against intercellular adhesion structures of epidermal keratinocytes. In pemphigus vulgaris (PV), the blisters are located in the suprabasal layer whereas in pemphigus foliaceus (PF), a clinically less severe disease, the blisters occur within the upper layers of the epidermis. In PV and PF, the AAb target the extracellular portions of desmoglein 3 (Dsg3) and Dsg1, respectively. AAb production in PV and PF is polyclonal and most AAb are of the IgG4 subclass in acute onset or active disease while patients in remission have mainly AAb of the IgG1 subtype. Evidence for the pathogenicity of these circulating AAb is provided by the observations that (1) the activity of pemphigus correlates with AAb titers, (2) newborns of mothers with active pemphigus temporarily exhibit blisters due to the transplacentar transfer of maternal AAb and (3) pemphigus-like lesions are induced in neonatal mice by transfer of IgG from PV patients. Clinically, pemphigus is characterized by extensive cutaneous blisters and erosions of the mucous membranes (PV). Patients with untreated pemphigus are prone to infections, loss of body fluids and proteins and to weight loss due to painful oral and esophageal erosions. The major therapeutic strategy in pemphigus is chronic immunosuppressive therapy with glucocorticosteroids in combination with immunosuppressive adjuvants.

Dapsone and sulfones in dermatology: overview and update

In their 60-year history, dapsone and the sulfones have been used as both antibacterial and anti-inflammatory agents. Dapsone has been used successfully to treat a range of dermatologic disorders, most successfully those characterized by abnormal neutrophil and eosinophil accumulation. This article reviews and updates the chemistry, pharmacokinetics, clinical application, mechanism of action, adverse effects, and drug interactions of dapsone and the sulfones in dermatology.

Immunodiagnosis of pemphigus and mucous membrane pemphigoid

Pemphigus and pemphigoid are two of a group of bullous diseases affecting oral mucosa and skin. Mucous membrane pemphigoid (MMP) comprises a heterogeneous group of disorders characterized by subepithelial separation and the deposition of immunoglobulins and complement along the basement membrane zone (BMZ). The target antigens in the epithelium and BMZ determine the nature of the condition, and recently there have been considerable improvements in our understanding of the BMZ antigenic composition. Pemphigus vulgaris (PV) is characterized by autoantibodies of the IgG isotype to the desmosomal glycoprotein desmoglein (Dsg) 3, whereas pemphigus foliaccus targets Dsg1, although at least 50% of PV patients have additional autoantibodies to Dsg1. The clinical phenotype appears to be determined by the relative amounts of Dsg1 and Dsg3. Patients with oral or mucosal PV have predominantly Dsg3 autoantibodies. The most frequently targeted antigen in MMP is bullous pemphigoid antigen 180 (BP180), although bullous pemphigoid antigen 230 (BP230), laminin 5, and beta 4 integrin are also involved. Circulating IgG and IgA antibodies may bind to different epitopes of BP180 namely the NC 16A domain or COOH -terminal domain. Pure ocular disease has been associated with IgA antibodies to a 45-kDa antigen and IgG antibodies to the 205-kDa antigen b4 integrin. The use of salt-split skin substrate enables differentiation between epidermal and dermal 'binders'. Since both the specificity and the antibody titer appear to have direct relationships with the disease severity, and a combination of clinical score and antibody titer provides valuable prognostic data, these investigations should be carried out on a more routine basis.

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.