Hypergammaglobulinaemic purpura associated with alcoholic liver cirrhosis.

Hypergammaglobulinaemic purpura (HP) is commonly found in Sjögren's syndrome. We report a rare association of HP arising in a patient with alcoholic liver cirrhosis. A 65-year-old man presented with palpable purpura on the legs. Histological examination of a biopsy taken from the purpura found leucocytoclastic vasculitis in the superficial and mid-dermis. The activity of the vasculitic skin lesions correlated with liver dysfunction. Increased IgA and IgG levels, and hypocomplementaemia, may account for the pathogenesis of the hypergammaglobulinaemic immune complex-mediated vasculitis in this case.

Use of domain-swapped molecules for conformational epitope mapping of desmoglein 3 in pemphigus vulgaris.

Pemphigus vulgaris is an autoimmune blistering disease caused by autoantibodies against desmoglein 3, a member of the desmosomal cadherin family. These autoantibodies recognize conformation-dependent epitopes on desmoglein 3. In this study we attempted to map the conformational epitopes of desmoglein 3 in pemphigus vulgaris using recombinant desmoglein 3 produced by the baculovirus expression system. We developed a series of domain-swapped molecules between desmoglein 3 and desmoglein 1, which have similar structures but distinct epitopes. These were developed by substituting deleted segmental regions of desmoglein 3 by the corresponding desmoglein 1. Thus domain-swapped molecules containing desmoglein 3 residues 1-403, 1-161, 163-566, and 405-566 were constructed and used as competitors for competition enzyme-linked immunosorbent assay against the entire extracellular domain of desmoglein 3 with 25 pemphigus vulgaris sera. Considering more than 50% absorption as significant, residues 1-403 and 1-161 showed significant absorption in 24 out of 25 (96%) and 18 out of 25 (72%) pemphigus vulgaris sera, respectively, whereas only one serum and no sera showed significant absorption by residues 163-566 and 405-566, respectively. Furthermore, no apparent change in their major epitopes was seen during the time course in four pemphigus vulgaris cases tested. These findings indicate that the domain-swapping approach is useful for conformational epitope mapping in pemphigus and that amino-terminal residues 1-161, which are considered to include a region essential for cell-cell adhesion in cadherins, contain the critical residues of the conformational epitope of desmoglein 3 recognized by the autoantibodies in pemphigus vulgaris sera.

Predominant IgG4 subclass in autoantibodies of pemphigus vulgaris and foliaceus.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune skin diseases caused by autoantibodies against desmoglein (Dsg) 3 and Dsg1. We have previously developed ELISAs using recombinant Dsg3 and Dsg1 expressed by baculovirus as a diagnostic tool for pemphigus. In this study, we determined the frequency of coexistence of IgA class as well as distribution of IgG subclass. Two out of 49 PV and PF sera tested had anti-Dsg1 IgA in addition to anti-Dsg1 IgG. Interestingly, one of them showed prominent pustular formation. Among IgG subclass, IgG4 was predominant and found in all of the 30 PV and 19 PF sera tested, followed by IgG1, detected in 25 out of 30 PV and 12 out of 19 PF sera. Even though IgG2 and IgG3 were detected in 13 and one PV and 6 and 4 PF sera, respectively, the ELISA titers had barely exceeded the cutoff value in most of the cases. There was no IgG subclass shift during the course of the disease in seven cases examined. These findings indicate that IgG4 subclass is the predominant autoantibodies in both PV and PF, while IgG1 is also frequently found.

Detection of IgA autoantibodies to desmogleins by an enzyme-linked immunosorbent assay: the presence of new minor subtypes of IgA pemphigus.

OBJECTIVE: To examine the frequency of antidesmoglein 1 (Dsg1) and antidesmoglein 3 (Dsg3) IgA autoantibodies in IgA pemphigus. DESIGN: We developed an enzyme-linked immunosorbent assay against recombinant Dsg1 and Dsg3 to detect IgA autoantibodies. PATIENTS: Twenty-two patients with IgA pemphigus were studied. Among them, 10 patients had subcorneal pustular dermatosis type, 9 patients had intraepidermal neutrophilic IgA dermatosis type, and 3 patients had pemphigus foliaceus-like clinical features. RESULTS: Of the 22 cases of IgA pemphigus, 3 cases were positive for anti-Dsg1 IgA antibodies and only 1 case was positive for anti-Dsg3 IgA antibodies. In those 4 cases, there were no IgA autoantibodies against other components of the keratinocyte cell surfaces because preincubation with the respective recombinant desmogleins removed the immunoreactivity on immunofluorescence. All 10 patients with subcorneal pustular dermatosis type IgA pemphigus were positive against desmocollin 1 expressed on COS-7 cells. No target antigen was detected in the other 8 cases. CONCLUSIONS: Desmogleins were recognized by IgA antibodies of a few patients with IgA pemphigus. Considering that subcorneal pustular dermatosis type IgA pemphigus recognizes desmocollin 1, autoimmune targets of IgA pemphigus are more heterogeneous than previously considered.

Thymoma with pemphigus foliaceus.

A 75-year-old Japanese woman was referred to us because of an anterior mediastinal mass. Crusts and shallow erosions developed 10 months earlier on her upper chest, back, and scalp. Pemphigus foliaceus was diagnosed based on histological examination of skin biopsy specimens and positivity for serum anti-desmoglein 1 antibody by enzyme-linked immunosorbent assay. Neurological examination and electromyography ruled out myasthenia gravis. Total thymectomy was performed, and the postoperative pathology studies showed mixed lymphoepithelial thymoma. One year after the resection, the eruption and alopecia improved and the serum anti-desmoglein 1 antibody titer decreased, suggesting a beneficial effect of thymectomy on thymoma-related pemphigus.

A case of erythema elevatum diutinum associated with B-cell lymphoma: a rare distribution involving palms, soles and nails.

We report a case of erythema elevatum diutinum (EED) in association with malignant B-cell lymphoma. A 62-year-old man developed EED with an unusual distribution involving the palms, soles and nails. Treatment with dapsone was effective for his skin and nails until he developed generalized lymphadenopathy which turned out to be malignant lymphoma. Many haematological diseases, e.g. IgA paraproteinaemia and myeloma, have been reported in association with EED, but not malignant lymphoma. Even though it may just be a coincidence, we would like to add malignant lymphoma as one of the diseases associated with EED because the activity of EED and malignant lymphoma fluctuated in parallel.

Dominant autoimmune epitopes recognized by pemphigus antibodies map to the N-terminal adhesive region of desmogleins.

Desmoglein (Dsg) is a cadherin-type adhesion molecule found in desmosomes. Dsg1 and Dsg3 are the target Ags in the autoimmune blistering diseases pemphigus foliaceus (PF) and pemphigus vulgaris (PV), respectively. To map conformational epitopes of Dsg1 and Dsg3 in PF and PV, we generated Dsg1- and Dsg3-domain-swapped molecules and point-mutated Dsg3 molecules with Dsg1-specific residues by baculovirus expression. The swapped domains were portions of the N-terminal extracellular domains of Dsg1 (1-496) and Dsg3 (1-566), which have similar structures but distinct epitopes. The binding of autoantibodies to the mutant molecules was assessed by competition ELISAs. Domain-swapped molecules containing the N-terminal 161 residues of Dsg1 and Dsg3 yielded >50% competition in 30/43 (69.8%) PF sera and 31/40 (77.5%) PV sera, respectively. Furthermore, removal of Abs against the 161 N-terminal residues of Dsg1 by immunoadsorption eliminated the ability of PF sera to induce cutaneous blisters in neonatal mice. Within these N-terminal regions, most of the epitopes were mapped to residues 26-87 of Dsg1 and 25-88 of Dsg3. Furthermore, a point-mutated Dsg3 molecule containing Dsg1-specific amino acid substitutions (His(25), Cys(28), Ala(29)) reacted with anti-Dsg1 IgG, thus defining one of the epitopes of Dsg1. Using the predicted three-dimensional structure of classic cadherins as a model, these findings suggest that the dominant autoimmune epitopes in both PF and PV are found in the N-terminal adhesive surfaces of Dsgs.

Pemphigus foliaceus with prominent neutrophilic pustules.

We describe four patients with generalized scaly and pustular skin lesions showing extensive neutrophilic infiltration in the subcorneal region of the epidermis. Immunofluorescence, immunoblot and enzyme-linked immunosorbent assay analyses detected IgG antibodies reacting exclusively with desmoglein 1, the pemphigus foliaceus antigen. This study indicates that pemphigus foliaceus may show prominent neutrophilic pustular skin lesions.