NEW TESTS FOR DIAGNOSTIC IMPROVEMENT IN AUTOIMMUNE BULLOUS DISEASES
- Chiara Bonaguri, Italy
Abstract
Background and Aims
Autoimmune blistering dermatoses (ABD) are a heterogeneous group of rare diseases clinically characterized by erosions and/or blisters on the skin and mucous membranes. In ABD the immune system produces autoantibodies (Abs) directed against cell-cell or cell-matrix adhesion molecules. More common ABD entities, pemphigus and bullous pemphigoid (BP), are identified by circulating and tissue-bound Abs against the desmosomal cadherins (mainly desmoglein 1 and 3 – DSG1/3) and dermal-epidermal junction components (BP180 and BP230).Several assays for the serological detection of anti-DSG1/ DSG3/ BP180/ BP230 Abs have been developed, however no gold standard assay exists, so a working set is needed.
Methods
We tested 104 patients suspected or diagnosed for ABD to evaluate the performance of three different assays: traditional IIF on monkey esophagus, innovative IIF BIOCHIP mosaic (an array of six different diagnostic substrates) and ELISA based on recombinant forms of the target antigens (DSG1/DSG3/BP180).
Results
We observed that Specialist Departments (Dermatology and Ophthalmology) and General Medicine Departments required different test profiles: ASA IIF 12% vs 88%, ELISA 68% vs 32% and BIOCHIP 100% vs 0%, respectively. The positive percentages for IIF ASA, ELISA and BIOCHIP were significantly different: 36%, 45% and 75%. The agreement between ASA IIF and Ag-specific test (ELISA-BIOCHIP) was 75%. 7/44 patients (16%) were ASA-/Ag+ and mainly represented by BP180+; instead 4/44 patients (9%) were ASA+/Ag- mainly represented by intercellular substance aspecific pattern.
Conclusions
Our results support the opportunity to perform very sensitive and specific tests, as Ag-specific assay, in order to achieve a definitive diagnosis.