Automated direct immunofluorescence analyses of skin biopsies

Advances in the diagnosis of autoimmune bullous dermatoses

Autoimmune bullous dermatoses are defined by autoantibodies directed against adhesion proteins in the epidermis or basement membrane zone, resulting in blister formation on the skin and mucosa. Diagnosis depends on lesional biopsy for histopathology and perilesional biopsy for direct immunofluorescence. Additional diagnostic methods include indirect immunofluorescence, enzyme-linked immunosorbent assay, and immunoblot (Western blot), which may be selected in specific clinical scenarios due to improved sensitivity and/or specificity. This contribution reviews the available evidence supporting the use of each method to provide a practical reference for clinicians when diagnosing autoimmune bullous disorders. Techniques and cost are reviewed, and newer diagnostic techniques with potential for clinical application are.

Blue light-emitting diode technology-operated microscopy is preferable to both short arc mercury lamp-operated microscopy and laser scanning confocal microscopy for direct immunofluorescence images evaluation in routinely diagnosing subepidermal autoimmune blistering diseases

Direct immunofluorescence (DIF) microscopy still is the gold standard in diagnosing and differentiating subepidermal autoimmune blistering diseases (SABDs) from other bullous diseases. New optical systems were developed that aim to facilitate DIF images evaluation. The aim of the study was to evaluate the usefulness of three fluorescence microscopy systems with different light source for routine diagnostics of SABDs with DIF. In total, perilesional tissue samples for DIF from 34 SABD patients were examined under the three commercial microscopy systems (short arc mercury lamp-operated microscopy-MLM, blue light-emitting diode technology-operated microscopy-bLED and laser scanning confocal microscopy-LSCM) for the detection and pattern analysis of IgA, IgG, IgG1, IgG4, C3 immunoreactants along the dermal-epidermal junction (DEJ) by three independent observers simultaneously. MLM, bLED, and LSCM provided comparable quality of disease-characterizing immunoreactants imaging (number of immunoreactant types detected and patterns of their deposition along DEJ were the same) but screening of slides was quicker using bLED than both LSCM and MLM, as statistical analysis indicated. It is concluded that bLED is an efficient and preferable system for routinely diagnosing SABDs cost-effectively. RESEARCH HIGHLIGHTS: New optical systems were developed that aim to facilitate direct immunofluorescence evaluation. Here, we evaluate the usefulness of three fluorescence microscopy systems with different light source for routine diagnostics concluding that that bLED is an efficient and preferable system.

Diagnosis of Autoimmune Blistering Diseases

Autoimmune skin blistering diseases (AIBD) are characterized by autoantibodies that are directed against structural proteins in the skin and adjacent mucous membranes. Some clinical signs are typical for a specific AIBD, however, correct diagnosis requires the detection of tissue-bound or circulating autoantibodies. The gold standard for diagnosis of AIBD is the detection of autoantibodies or complement component 3 by direct immunofluorescence (DIF) microscopy of a perilesional biopsy. Circulating antibodies can be detected via indirect immunofluorescence (IIF) microscopy of different tissue substrates including human skin, monkey esophagus, and more recently, recombinant forms of the different target antigens. Latter are also employed in various commercial ELISA systems and by immunoblotting in in-house assays available in specialized laboratories. ELISA systems are also particularly valuable for monitoring of the disease activity during the disease course which can be helpful for treatment decisions. Exact diagnosis is essential for both treatment and prognosis, since some AIBD are associated with malign tumors such as paraneoplastic pemphigus and anti-laminin 332 mucous membrane pemphigoid. This review presents clinical and immunopathological features of AIBD for the state-of the art diagnosis of these disorders.

The Growing Incidence of Bullous Pemphigoid: Overview and Potential Explanations

Bullous pemphigoid (BP) is the most common type of subepidermal autoimmune bullous diseases. BP characteristically affects the elderly and is seen mainly in patients older than 70 years. While the annual incidence of BP has been estimated to be between 2.4 and 23 cases per million in the general population, it rises exponentially to 190-312 cases per million in individuals older than 80 years. In addition, a growing body of evidence reports a remarkable trend of increased incidence of BP, showing a 1.9- to 4.3-fold rise over the past two decades. This demonstrable increase warrants a higher awareness of the increased risk to develop BP. This review summarizes the current understanding of the epidemiological features of BP and sheds light on the putative explanations for its growing incidence.