Spectrum of autoantibodies other than anti‐desmoglein in pemphigus patients

Background Pemphigus is a life‐threatening autoimmune blistering disease mediated by autoantibodies against adhesion molecule of the skin. Its concurrence with systemic and organ‐specific autoimmune disease was described in case reports. Objectives To evaluate the presence of a broad spectrum of organ‐specific and non‐organ‐specific autoantibodies other than anti‐desmoglein antibodies in pemphigus patients. Patients and methods Serum samples were obtained from 105 pemphigus foliaceus (PF) patients, 51 pemphigus vulgaris (PV) patients and 50 controls. Both indirect immunofluorescence assay and ELISA were used to assess the presence of autoantibodies related to connective tissue diseases, autoimmune hepatitis, vasculitis, rheumatoid arthritis, coeliac disease, diabetes and thyroiditis. Results Significant difference was observed between the three groups for anti‐thyroglobulin antibodies in the pemphigus foliaceus group (18% vs. 4%, P = 0.03). A significantly higher occurrence of IgM anti‐cardiolipin (P = 0.03), IgG anti‐reticulin (P = 0.01) and IgG anti‐gliadin antibodies (P = 0.008) were observed in the PV group. Cases with more than four autoantibodies were frequently positives for both anti‐desmoglein 1 and anti‐desmoglein 3. Conclusion Autoantibodies other than anti‐desmoglein antibodies are not rare in pemphigus patients. Clinical and serological follow‐up of pemphigus patients with positive autoantibodies are needed to clarify their impact in disease evolution.     

Four mild but refractory cases of pemphigus foliaceus successfully treated with intravenous immunoglobulin

Intravenous immunoglobulin (IVIG) is a potential second line of therapy for pemphigus, with increasing evidence of its effectiveness and safety, although oral corticosteroids remain the first treatment for pemphigus. IVIG is usually applied in severe cases of pemphigus, particularly pemphigus vulgaris (PV). Pemphigus foliaceus (PF) caused by immunoglobulin PF autoantibodies to desmoglein 1 (Dsg1) is usually milder than PV. However, PF cases are occasionally resistant to corticosteroids and require long‐term treatment to control the disease, leading to various adverse effects. IVIG was used in patients with relatively mild PF, who were resistant to therapies with corticosteroids and dapsone. We assessed the disease severity by Pemphigus Disease Area Index (PDAI) and measured anti‐Dsg1 antibody indices by enzyme‐linked immunosorbent assay, before and 4 months after IVIG. Four Japanese female PF patients (57.3 ± 8.6 years) were treated with a single cycle of IVIG (400 mg/kg per day for five consecutive days) in combination with the previous therapies. Within 1–2 months of addition of IVIG, all PF cases showed remarkable improvement of skin lesions, and PDAI also markedly decreased. For 2 years after IVIG, no apparent exacerbation was observed. Anti‐Dsg1 antibody indices decreased in all cases during the 2 years. IVIG could be a potential treatment for not only severe cases of PV but also mild and refractory cases of PF. IVIG may trigger the shift from intractable condition to remission via non‐pathogenic anti‐Dsg1 antibodies or some mechanisms excluding anti‐Dsg1 antibody.     

A novel lateral flow immunoassay for the rapid detection of anti‐Dsg3 IgG serum autoantibodies in pemphigus vulgaris

Pemphigus vulgaris (PV) is a severe autoimmune blistering disease of the skin and mucous membranes. As autoantibodies play an essential role in the disease pathogenesis, the serological detection of anti‐desmoglein 3 IgG represents a central tool in the diagnosis of the disease. In this study, we show the validation of a novel lateral flow immunoassay (LFIA) which rapidly detects anti‐desmoglein 3 (Dsg3) IgG in human serum. In contrast to other diagnostic procedures, the assay is compact and simple to perform and delivers a fast ”yes” or “no” answer within 10 minutes without additional hardware requirements for test evaluation. For validation, a blinded collection of 200 sera including 100 sera from 14 PV patients, 75 sera from 24 bullous pemphigoid patients and 25 sera from 6 patients with pemphigus foliaceus collected at different time points during disease was used. Presence or non‐presence of anti‐Dsg3 IgG within sera was confirmed using a commercially available Dsg3‐ELISA. For qualitative evaluation, Dsg3‐LFIA test results were assessed by two independent groups of human observers. Furthermore, quantitative evaluation using POCScan reader was applied. The Dsg3‐LFIA demonstrated reliable test results with a sensitivity and specificity of 78.1% and 97.1%, respectively. Test results from POCScan and human observers showed a substantial agreement. The Dsg3‐LFIA represents a new diagnostic tool for the immediate and reliable detection of anti‐desmoglein 3 serum IgG autoantibodies that does not require additional hardware. Further prospective trials are warranted to validate the Dsg3 LFIA in pemphigus.     

A 6‐year treatment experience for pemphigus: retrospective study of 69 Chinese patients

There is a lack of data on treatment and prognosis of pemphigus in China. The aim of this study was to evaluate long‐term follow‐up and prognosis of pemphigus. Forty‐seven inpatients with pemphigus vulgaris (PV) and 22 with pemphigus foliaceus (PF) were recruited in this retrospective study. The average age at onset was 51.6 and 54.9 years in PV and PF, respectively. High‐dose systemic steroids were administered in 47 PV and 21 PF, of which 18 PV and 8 PF with adjuvant therapies. CD4 lymphocytopenia was found in 5 PV and 2 PF patients at admission and successfully treated by intravenous thymopentin daily. During a mean follow‐up of 37.1 months, 41 PV and 19 PF reached remission, 30 PV and 9 PF relapsed, 4 PV and 2 PF died. Major causes of death were relapse of pemphigus due to discontinuation of oral steroids by the patients themselves (four cases) and severe infections (two cases, one with severe CD4 lymphocytopenia). The 1‐year mortality rate of PV and PF was 8.5% and 4.5%, respectively. Cox regression analysis indicated that age at onset of pemphigus was an independent risk factor related to the elevated mortality. Our report confirmed the high mortality rate of pemphigus in a Chinese population and stressed that patient education was urgently needed to prevent relapses and deaths.     

The role of IVIg treatment in severe pemphigus vulgaris

BACKGROUND: High-dose intravenous immunoglobulin (IVIg) has become a part of the treatment armentarium in pemphigus vulgaris (PV). Some consider IVIg as an adjuvant steroid sparing agent in PV, while others as disease modifying that can be used as monotherapy. METHODS: We report our experience with a series of 12 PV patients with severe disease treated with IVIg as an adjuvant therapy. RESULTS: Ten of 12 patients (83%) showed response to six cycles of IVIg, six (50%) having complete remission and four (33%) having a partial response. This response rate is concordant with previous reports. The therapy was well tolerated. In all 12 patients, treatment with IVIg allowed a gradual reduction of prednisone dose compared with baseline levels. CONCLUSION: IVIg treatment was beneficial as a steroid sparing agent in our series of patients with severe PV.     

The efficacy of nicotinamide gel 4% as an adjuvant therapy in the treatment of cutaneous erosions of pemphigus vulgaris

The high rate of morbidity and mortality resulting from long‐term use of corticosteroids in pemphigus vulgaris (PV) warrants discovery of a new treatment strategy. Based on the pathophysiology of PV, nicotinamide can block the process of blister formation through its anti‐inflammatory properties. This study was conducted to evaluate the clinical effectiveness of nicotinamide gel in the treatment of skin lesions of PV. In a double‐blind, placebo‐controlled study, eight PV patients with a total of 60 skin lesions were treated by either nicotinamide or placebo gel. After 30 days of treatment, epithelialization index of the two groups was compared. The mean of the epithelialization index in skin lesions that received nicotinamide was significantly higher than that of the placebo group (26 vs. –5.8, p < 0.001). Our results were suggestive that nicotinamide gel can effectively be used as an adjunctive treatment for PV lesions.     

Neonatal pemphigus vulgaris with extensive mucocutaneous lesions from a mother with oral pemphigus vulgaris

The clinical phenotype of pemphigus is well explained by the combination of desmoglein (Dsg) 1 and Dsg3 distribution pattern and antiDsg autoantibody profile (Dsg compensation theory). It has been reported that neonatal skin has a similar Dsg distribution pattern to adult mucosal epithelia. We describe a newborn girl with mucocutaneous pemphigus vulgaris (PV) from a mother with mucosal dominant PV. The mother had had painful oral erosions for at least 7 months. Histopathological examination and direct and indirect immunofluorescence studies confirmed the diagnosis of PV and neonatal PV in the mother and daughter, respectively. The mother had a high titre of anti-Dsg3 IgG and a low titre of antiDsg1 IgG, while the neonate had only a high titre of anti-Dsg3 IgG, but no detectable antiDsg1 IgG. AntiDsg3 IgG, which caused the oral dominant phenotype in the mother, induced extensive oral as well as cutaneous lesions in the neonate. Our case provides clinical evidence for the Dsg compensation theory in neonatal PV.     

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.     

An 'n-of-1' placebo-controlled crossover trial of intravenous immunoglobulin as adjuvant therapy in refractory pemphigus vulgaris

Background  Pemphigus vulgaris (PV) is an organ-specific autoimmune blistering mucocutaneous disorder that is potentially fatal. High-dose intravenous immunoglobulin (IVIg) is increasingly used in the treatment of autoimmune diseases and it has been reported that it may also be effective in PV.
Objectives  To evaluate prospectively the efficacy of IVIg for PV using an 'n-of-1' placebo-controlled trial.
Methods  A randomized, placebo-controlled, crossover trial of IVIg was conducted in a single patient with severe PV, comprising two phases of six consecutive months of either IVIg or placebo infusion. Before the commencement of the trial, the patient had received 18 months of IVIg but concerns about the continuing therapeutic efficacy of IVIg led to the double-blind placebo-controlled 'n-of-1' trial of IVIg.
Results  Pemphigus autoantibody titres were significantly higher when on placebo compared with IVIg treatment (median 1 : 80 vs. 1 : 20, P  =   0·007), desmoglein 3 (126 vs. 79, P  =   0·004) and desmoglein 1 antibody levels (126 vs. 94, P  =   0·004). There was a significant improvement in subjective disease activity scores while on IVIg compared with placebo (mean overall score 11·6 vs. 20·6, P  <   0·0001).
Conclusions  The results of this study confirm a beneficial effect of IVIg in the management of refractory PV.     

Rituximab as the treatment of pemphigus vulgaris in the COVID‐19 pandemic era: A narrative review

Pemphigus vulgaris (PV), an autoimmune blistering disease is treated with immunosuppressive medications. As the immunosuppressive effect of rituximab, the first‐line therapy of PV, lasts more than 6 months, many concerns have raised due to the ongoing novel coronavirus disease (COVID‐19) pandemic. With this background, our objective was to review the currently available literature as well as important websites for the evidence related to rituximab, PV and COVID‐19, adverse effects associated with drugs, and relevant guidelines. “PubMed” and “Google Scholar” database were systematically searched for retrieving all articles related to anti‐CD20 therapy in pemphigus vulgaris and COVID‐19 published up to 14 July 2020. A total of seven clinical studies are performed with anti‐CD20 therapy in COVID‐19, three of which are performed on pemphigus patients, and have shown concerns employing rituximab in patients with COVID‐19. Evidence for treating PV patients with rituximab in COVID‐19 pandemic is limited. Until sufficient evidence or guideline for pemphigus and COVID‐19 treatment is available, we advocate caution commencing rituximab in patients with pemphigus, due to the reported adverse outcomes.     

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.     

Low‐dose rituximab and concurrent adjuvant therapy for pemphigus: Protocol and single‐centre long‐term review of nine patients

Pemphigus is an autoimmune B‐cell mediated blistering disease associated with significant morbidity and mortality. Rituximab has proven effective for the treatment of steroid‐refractory pemphigus, although there is controversy over the optimum dosing protocol. Additionally, effective disease control often requires long‐term immunosuppression, even in disease‐free periods. We present a case series of a single‐centre long‐term follow up of nine patients with pemphigus, treated with two 500‐mg doses of rituximab separated by 14 days along with concurrent adjuvant therapy. In all these patients, low‐dose rituximab resulted in B‐cell depletion, along with a reduction in blistering disease. Three of these patients required repeat dosing cycles due to either relapsed disease or incomplete disease control following the first dosing cycle, and have remained disease free up to 154 weeks thus far. Six patients developed minor infections during the course of their treatment, but no major complications were observed.     

Enteric‐coated mycophenolate sodium in the treatment of refractory pemphigus

Background One of the major goals of pemphigus therapy is to reduce the patient’s cumulative exposure to systemic corticosteroids. To investigate the efficacy of enteric‐coated mycophenolate sodium (EC‐MPS), 10 patients with active, refractory pemphigus vulgaris (PV) or foliaceous (PF) were treated with EC‐MPS (1440 mg daily) and prednisone (75 mg daily) over 18 months. Observations Following EC‐MPS/prednisone therapy, disease progression was inhibited between days 30 and 45 in 9/10 patients (8 PV; 1 PF). At 18 months, 8/9 PV patients had clinically quiescent disease; EC‐MPS therapy was no longer required in two patients as a result of disease remission. The remaining PV patient showed no response to treatment. The PF patient also had clinically quiescent disease but with high levels of anti‐desmoglein‐1. ECMPS dose was reduced to 720 mg daily in 4/9 patients by month 6. Average daily prednisone requirement decreased to 25 mg at 6 months and to 15 mg at 18 months. Three adverse events were reported: headache (two cases; one mild and one moderate) and significant increase in blood glucose (one case; moderate). Conclusions Enteric‐coated mycophenolate sodium is effective and safe as an adjuvant therapy in patients with refractory pemphigus and may be effective even in patients whose disease is unresponsive to azathioprine.     

Low-dose rituximab is effective in pemphigus

Background Rituximab, an anti‐CD20 antibody, was shown in open series studies to be effective in treating pemphigus at a dose of 4 × 375 mg m^?2 as approved for B‐cell malignancies. Objectives We investigated whether a lower dose of rituximab is also effective for pemphigus. Methods Patients with pemphigus were treated with a single course of two infusions of rituximab (500 mg each) at an interval of 2 weeks. Clinical consensus late end points, B‐cell number, desmoglein 1 and desmoglein 3 indices were monitored. Results We enrolled 15 patients in the study: three with pemphigus foliaceus (PF) and 12 with pemphigus vulgaris (PV). The follow‐up was 32–152 weeks (median 94). All 15 patients responded to therapy. Eight patients achieved complete remission in a median period of 51 weeks (four on minimal therapy, four off therapy). Seven patients achieved partial remission in a median period of 34·5 weeks (five on minimal therapy, two off therapy). Relapses (40%) were seen between 53 and 103 weeks (median 97) after start of therapy. B‐cell numbers dropped to < 1% after first infusion, and remained undetectable in patients with sustained remission. The antidesmoglein 1 index correlated well with the clinical severity in PF, but this was less obvious in PV. Conclusions A low dose of rituximab is an effective and safe treatment for pemphigus. Relapses may occur, mostly at the end of the second year. Cost–effectiveness studies with a long follow‐up are required to determine the proper dosage of this expensive drug in pemphigus.     

Methylprednisolone pulse therapy plus adjuvant therapy for pemphigus vulgaris: an analysis of 10 years' experience on 312 patients

Steroid pulse therapy has shown satisfactory efficacy and safety in treating pemphigus vulgaris (PV). However, there is a paucity of data about the efficacy and safety of methylprednisolone, despite its frequent administration. The aim of this study is to evaluate the efficacy and safety of steroid pulse therapy in treating PV. In this 10‐year retrospective cohort study, 312 patients with PV, who had received methylprednisolone pulse therapy, were included. Data of pulse therapy sessions, adjuvant medications, dosages, remission rates, complications, and mortalities were collected from all patients. A total of 276 patients out of 312 underwent the final follow‐up at least 6 months after the last session of pulse therapy. Complete remission off therapy was achieved in 83 patients (30%), and 152 patients (55%) had complete remission on therapy. About 29 (10.5%) patients had lesions of pemphigus at the time of the study follow‐up, and 26.8% of remained patients were on the minimal therapy. Methylprednisolone pulse therapy could be considered as an option for proper control of PV in severe cases. It might lead to shorter periods of hospitalization and reduce the need to take long‐term high‐dose oral steroid therapy.     

Klinik und Immunpathologie bei 48 Patienten mit Pemphigus

Background and Objective. Pemphigus is a rare intraepidermal autoimmune bullous disease. Two major variants, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), are distinguished. The aim of this study was to document the clinical and immunpathological findings in all pemphigus patients who were diagnosed in the Department of Dermatology at the University of Würzburg over the past 10 years. Patients/Methods. Based on a retrospective study, clinical and immunpathological findings in 48 patients with pemphigus were recorded. All patients had positive findings by direct and/or indirect immunfluorescence microscopy. Results. Between January 1989 and August 1998, 48 patients were diagnosed with pemphigus at our institution; 31 patients had PV and 17 PF. The average age (±standard deviation) of PV patients was 55 (±17) and of PF patients 60 (±12) years. All PV patients showed involvement of mucous membranes and in 65% of cases, the skin was also involved. In contrast, PF patients had involvement only of the skin. By direct immunfluorescence microscopy, intercellular deposits of IgG and C3 were detected in 89% and 78% of PV cases, respectively. In PF, intercellular deposits of IgG were found in 94% and of C3 in 75% of cases. By indirect immunfluorescence microscopy on monkey esophagus, 94% of the PV and 88% of the PF patients revealed circulating serum antibodies. In 30 patients, we characterized the immune response by ELISA using recombinant desmoglein 1 and 3. All PF sera showed autoantibodies against desmoglein 1 and all PV sera against desmoglein 3. In PV with both mucous membrane and skin involvement, antibodies to both desmoglein 3 and 1 were detected. Conclusions. Our results confirm the correlation of the autoantibody profile with the clinical phenotype of pemphigus.     

Adjuvant rituximab treatment for pemphigus: A retrospective study of 45 patients at a single center with long‐term follow up

To evaluate the long‐term outcomes of rituximab in the treatment of pemphigus and the influence of disease duration and different dose of rituximab on the clinical response, 45 patients with refractory pemphigus treated with at least one cycle of two infusions of rituximab (375 mg/m² per infusion weekly) were retrospectively studied. All patients were followed up for more than 2 years. All patients achieved complete or partial remission within 8 months of the first cycle. Thirty‐four (76%) patients relapsed at a median of 17 months. All patients who received additional cycles after relapse achieved new remissions. Early use of rituximab within 1 year of disease duration and high‐dose therapy induced better outcomes, although the results in early use were not statistically significant. Acute respiratory distress syndrome occurred in one patient. Rituximab is effective in treating pemphigus, but relapses are frequent during long‐term follow up, and additional cycles are beneficial in relapsed cases. Early and high‐dose rituximab therapy may be more effective.     

免疫球蛋白治疗难治性寻常型天疱疮的疗效观察

目的 评价静脉免疫球蛋白治疗难治性寻常型天疱疮的临床及其意义.方法 经临床、病理和直接免疫荧光、间接免疫荧光确诊为活动期寻常型天疱疮的12例患者,每天静脉注射免疫球蛋白400 mg/kg,连续5天,每4周1次为1疗程.所有患者在治疗时停用环磷酰胺或硫唑嘌呤.结果 12例中10例在开始静脉免疫球蛋白冲击治疗1周后病情控制.4周后糖皮质激素剂量减少30%.11例无明显不良反应,仅1例患者在输液开始30分钟内出现头痛、面红、心动过速,调整输液速度后缓解.血清中抗桥粒芯糖蛋白抗体-3抗体浓度(滴度)迅速降低,1周下降54%,2周下降70%,3周下降78%.抗桥粒芯糖蛋白抗体-3抗体下降而总IgG水平不变.结论 静脉免疫球蛋白可迅速控制难治性寻常型天疱疮病情,不良反应轻且有自限性,是治疗该病的有效方法之一.     

Pemphigus vulgaris with psoriasis vulgaris successfully treated with methotrexate and low‐dose methylprednisolone

Psoriasis and pemphigus are clinically well‐characterized chronic, inflammatory skin diseases. Many case reports have described the coexistence of psoriasis and bullous pemphigoid. However, the present report is about a rare case of pemphigus vulgaris in a patient with psoriasis vulgaris. We had a 68‐year‐old male psoriatic patient who developed blisters lesions and erosions on the trunk and extremities. The histopathology of a blister lesion showed the intraepidermal blisters that contained serous fluid and inflammatory cells. Both of desmoglein core protein 1 antibody and desmoglein core protein 3 antibody were detected. Diagnoses of pemphigus vulgaris and psoriasis vulgaris were made. The patient was treated with methotrexate (12.5 mg/week) and methylprednisone (16 mg/day) after his admission. Two weeks after admission, the patient's lesions gradually subsided. This case reminds us that the therapeutic effect of pemphigus vulgaris may be related to the incidence of psoriasis.     

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.