Antidesmoplakin antibodies in pemphigus vulgaris.

BACKGROUND: Besides being present in paraneoplastic pemphigus (PNP), circulating antidesmoplakin (DP) antibodies have been found anecdotally in other bullous diseases, including pemphigus foliaceus and pemphigus vulgaris. OBJECTIVES: To verify how frequent anti-DP antibodies are in pemphigus vulgaris. METHODS: We studied 48 sera from patients with proven pemphigus vulgaris (29 mucosal dominant pemphigus and 19 mucocutaneous pemphigus) by indirect immunofluorescence (IIF) with rat bladder epithelium (RBE) as a substrate and by immunoblotting (IB) on human keratinocyte cultures enriched in DP. RESULTS: Ten sera (21%) were positive in IIF on RBE. By IB, eight sera proved to have antibodies to both DP I (250 kDa) and DP II (210 kDa), one serum had antibodies directed to DP I only, and two sera to DP II only. CONCLUSIONS: Our data confirm that RBE is not a specific IIF substrate for the serological diagnosis of PNP. It remains a sensitive and specific substrate for the detection of anti-DP antibodies, which, in patients with pemphigus vulgaris, are probably caused by an epitope-spreading phenomenon.

Role of soluble and cell surface molecules in the pathogenesis of autoimmune skin diseases.

The skin is one of the most commonly involved tissue in rheumatic autoimmune diseases. Different mechanisms are thought to be implicated in the pathogenesis of skin lesions. In genetically predisposed individuals, ultraviolet (UV) light can contribute to the induction of skin lesions via an inflammatory process. UV light promotes the release of cytokines by keratinocytes and the induction of adhesion molecules on the surface of epidermal cells initiating a cascade of inflammatory events and recruiting immunoinflammatory cells into the skin. In this review data regarding the expression of TNF-alpha in lesional skin tissue from subacute cutaneous lupus erythematosus patients and the role of interferons in the pathogenesis of skin manifestations of rheumatic autoimmune diseases are reported. In addition, an overview on the expression of cellular adhesion molecules in these diseases is provided.UV light can also induce apoptosis in keratinocytes. During this cell death several enzymes became activated. Among them, desoxyribonuclease (DNase) is an enzyme involved in degrading DNA during apoptosis. Data regarding the activity of DNAse in patients with cutaneous lupus erythematosus as a possible risk factor for the development of systemic disease are here reported.

Antidouble-stranded DNA isotypes in lupus erythematosus patients with prevalent cutaneous presentation.

BACKGROUND: Antidouble-stranded DNA antibodies (anti-dsDNA Ab), in particular of the IgG isotype, are usually considered a marker of systemic lupus erythematosus and often correlate with the disease activity. OBJECTIVES: To determine IgG, IgA and IgM anti-dsDNA Ab in a group of 330 patients with lupus erythematosus and prevalent cutaneous lesions. METHODS: The titre of anti-dsDNA Ab was determined by enzyme-linked immunosorbent assay, and disease activity was assessed by means of the systemic lupus activity measure. RESULTS: One hundred and six patients had anti-dsDNA Ab. Thirty-nine patients had antibodies of all three isotypes of immunoglobulins, 17 had IgG + IgM, five IgG + IgA, and two IgA + IgM. Forty-three patients had a single isotype of anti-dsDNA Ab. Patients with systemic disease and higher disease activity had antibodies of all three isotypes of immunoglobulins or of IgG isotype. Remarkably, anti-dsDNA Ab of the IgA isotype, alone or associated with IgM, marked dermatological patients with low disease activity, but often with disquieting clinical and/or laboratory alterations. CONCLUSIONS: These results indicate a correlation between disease activity and both frequency and isotype of anti-dsDNA Ab.

Fosinopril as a possible pemphigus-inducing drug.

Fosinopril has recently been added to the angiotensin-converting enzyme inhibitors inducing pemphigus. The observation of a patient in whom pemphigus vulgaris (PV) worsened after taking fosinopril prompted us to study an experimental way to assess its responsibility. Slices of normal human skin (NHS) were simultaneously incubated for 2, 6, 12 and 24 h at 4 degrees C with progressively diluted fosinopril and captopril solutions and used as indirect immunofluorescence (IIF) substrates for 2 sera containing anti-desmoglein-3 (anti-Dsg3) antibodies at a dilution of 1/160. With captopril, IIF was negative, irrespective of dilution and time of incubation. Only at 1/40,000 dilution was IIF positive. With fosinopril, IIF was negative for the 2- and 6-hour-long incubations but turned positive after 12 h and so remained with all other solutions and incubation times. IIF negativity with captopril suggests that anti-Dsg3 antibodies contained in the PV sera were unable to find molecules in NHS to bind to. Captopril would therefore induce acantholysis by blocking the adhesion molecules. With fosinopril, instead, a partial block of the adhesion molecules was seen only with the very concentrated solution, unlikely to occur in vivo. Fosinopril, therefore, is probably unable to block the adhesion molecules in vivo. Our method might be used to verify the acantholytic properties of a drug.

Scleroderma subsets are best detected by the simultaneous analysis of the autoantibody profile using commercial ELISA.

OBJECTIVE: Antinuclear antibodies are often present in patients with systemic sclerosis but do not provide useful prognostic information if studied individually. Although an autoantibody profile should be studied, this has never been done in a large series of patients. METHODS: Anticentromere, anti-topoisomerase-I, anti-extractable-nuclear-antigen, antihistone and anticardiolipin antibodies were studied by means of enzyme immunosorbent assay in 90 systemic sclerosis patients. RESULTS: We confirmed that anticentromere antibodies characterize limited forms of the disease with less frequent visceral involvement while anti-topoisomerase-I antibodies characterize diffuse forms with severe gastrointestinal, heart and lung involvement. Antihistone antibodies alone or associated with anticentromere antibodies characterize a disease subset with more frequent visceral involvement and a probably poor outcome. Patients with anticardiolipin antibodies, instead, did not display severer heart or vascular involvement. CONCLUSIONS: Systemic sclerosis patients are often found to have antinuclear antibodies. In addition to the well-known disease subsets identified by anti-topoisomerase-I and anticentromere antibodies, another one can be established, characterized by antihistone antibodies often associated with anticentromere antibodies. Patients displaying this profile have high prevalence of lung, kidney and heart involvement.

Rat bladder epithelium: a sensitive substrate for indirect immunofluorescence of bullous pemphigoid.

Serological diagnosis of bullous pemphigoid is based on immunoblotting or indirect immunofluorescence on normal human salt-split skin. These methods are expensive or time-consuming and not available as a routine test in all laboratories. We used rat bladder epithelium as substrate for indirect immunofluorescence and compared it with other substrates and with immunoblotting. Twenty-nine bullous pemphigoid sera were studied on rat bladder epithelium, monkey oesophagus, salt-split skin and with immunoblotting on human keratinocyte cultures. Indirect immunofluorescence on rat bladder epithelium proved to be more sensitive (72%) than on monkey oesophagus alone (45%) and less sensitive than on salt-split skin (97%). Rat bladder epithelium, when tested on 41 sera of a control group, showed a very high specificity: 2/41 (95%). In combination with immunoblotting on keratinocyte extracts, indirect immunofluorescence on rat bladder epithelium allowed 93% of sera to be recognized, a value close to the salt-split skin alone. Rat bladder epithelium appears to be a more sensitive substrate than monkey oesophagus for the diagnosis of bullous pemphigoid and, although less specific, it is easier and faster than using salt-split skin, which remains indispensable to distinguish bullous pemphigoid from epidermolysis bullosa acquisita.

Counterimmunoelectrophoresis, ELISA and immunoblotting detection of anti-Ro/SSA antibodies in subacute cutaneous lupus erythematosus. A comparative study.

Patients with subacute cutaneous lupus erythematosus (SCLE) have circulating antibodies to Ro/SSA directed to two antigenically distinct ribonucleoproteins of 60 kDa and 52 kDa. Three laboratory tests may be used to detect anti-Ro/SSA antibodies: counterimmunoelectrophoresis (CIE), enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB). Their relative efficacy and clinical correlations were ascertained. We determined anti-Ro/SSA antibodies with CIE, with two different ELISA methods (ELISA 1 and 2) and with IB in 29 SCLE patients. Anti-52 kDa and -60 kDa Ro/SSA antibodies were also assayed with IB. In addition, we determined antinuclear antibodies with indirect immunofluorescence, anti-Sm, anti-RNP, anti-La/SSB and anti-Ro/SSA antibodies with CIE and ELISA, and anti-nDNA and cardiolipin antibodies using an ELISA method. CIE detected anti-Ro/SSA antibodies in 22 patients while ELISA 1 and 2 did so in 17 and 18 patients, respectively. In five patients, IB revealed a reactivity to 60 kDa polypeptides and in two, a reactivity to 52 kDa polypeptides. Of these seven patients, four had a myocardial infarction. Of these, two reacted to the 52 kDa antigen and two to the 60 kDa antigen. A combination of techniques was often needed to detect all specificities. ELISA proved to be very specific and sensitive. The IB technique detected a group of patients with myocardial infarction. A case-control study is needed to confirm the data of cardiac involvement.

Antihistone antibodies in scleroderma.

BACKGROUND: Antihistone antibodies (AHA) are usually considered the serological marker of drug-induced lupus erythematosus, but recently they have been found in patients with systemic scleroderma (SSc) and morphea. OBJECTIVE AND METHODS: We determined AHA in 43 patients with SSc, 4 patients with overlap syndrome and 11 with morphea. RESULTS AND CONCLUSIONS: AHA were demonstrated in 41.8% of the SSc patients and in 36.3% of the morphea patients. Only 1 patient with overlap syndrome had AHA. Our SSc patients with AHA had frequent cardiac and renal involvements suggesting a prognostic value of AHA. In our morphea patients AHA did not correlate with clinical features.