BackgroundThe BIOCHIP is a novel multiplex indirect immunofluorescence technique used in the serological diagnosis of bullous pemphigoid and pemphigus. The BIOCHIP method combines the screening of autoantibodies and target antigen‐specific substrates in a single miniature incubation field.ObjectiveTo evaluate the diagnostic accuracy of the new immunofluorescence BIOCHIP multiplex tool in pemphigus and bullous pemphigoid.MethodsFor the validation of the BIOCHIP, sera from patients with BP (n = 38), PF (n = 8) and pemphigus vulgaris (PV) (n = 23) were used. In addition, sera from disease control patients (n = 63) and healthy volunteers (n = 39) were used. The multiplex BIOCHIP and direct immunofluorescence (DIF) were performed for all BP, PF and PV patients. Additional indirect immunofluorescence (IIF) was performed on patients with BP, and ELISA was performed on patients with pemphigus.ResultsThe BIOCHIP mosaic showed a sensitivity of 86.8% and specificity of 85% for BP180 or BP230 being positive in BP. It demonstrated a sensitivity of 75% and specificity of 97.7% for Dsg1 in PF. The BIOCHIP was found to have a sensitivity of 60.9% and specificity of 73.6% for Dsg3 in PV.ConclusionThe BIOCHIP mosaic‐based immunofluorescence test is potentially a simple, time and effort saving test that can aid in the diagnosis and screening of BP, PV and PF. However, there is potential for interpretation bias and a learning curve that needs to be taken into consideration.

The immunoassays that are available for the serological diagnosis of the more common subtypes of autoimmune blistering diseases such as pemphigus vulgaris (PV) and pemphigus foliaceus (PF) include enzyme-linked immunosorbent assay (ELISA) testing to specific antigens desmoglein (Dsg)1 and Dsg3, direct immunofluorescence (DIF), indirect immunofluorescence (IIF), and immunoblotting. A review of the literature on the biochip assay was conducted. Six studies investigated the validity of a new biochip, mosaic-based, IIF test in patients with pemphigus and demonstrated its relatively high sensitivity and specificity (Dsg3: 97.62-100%, 99.6-100%; Dsg1: 90%, 100%) in comparison with ELISA (Dsg3: 81-100%, 94-100%; Dsg1: 69-100%, 61.1-100%), and/or IIF (PV: 75-100%, 91.8-100%; PF: 67-100%) using suitable substrates. So far, validation studies of the biochip have been conducted in four countries (Germany, Italy, Turkey, and Poland) but none in the southern hemisphere. Caucasian patients were recruited as normal controls for these studies; thus, the diagnostic value of the biochip remains uncertain in population groups of other ethnicities. A range of disease control patients were recruited including patients with linear immunoglobulin A dermatosis, psoriasis, discoid lupus erythematosus, lichen planus, and noninflammatory skin diseases (e.g., squamous cell carcinoma, basal cell carcinoma, and vascular leg ulcers). Prospective studies with control patients from a diverse range of ethnicities are needed to better validate the biochip.

The BIOCHIP (Dermatology Mosaic 7, EUROIMMUN, Lubeck, Germany) is a novel multiplex indirect immunofluorescence technique used in the serological diagnosis of bullous pemphigoid. The BIOCHIP method combines the screening of several autoantibodies and target antigen-specific substrates in a single miniature incubation field to allow for simultaneous processing of the most common autoimmune bullous diseases autoantibodies using a single investigation. This manuscript reviews the literature on the validity of the BIOCHIP in the diagnosis of bullous pemphigoid. A systematic search for journal articles comparing the sensitivity and specificity of diagnostic tests for bullous pemphigoid patients was conducted in online databases via the Ovid SP search interfaces. The literature search generated 745 articles of which 189 were deemed relevant. Among the relevant articles, seven studies investigated the validity of the BIOCHIP indirect immunofluorescent test in the diagnosis of bullous pemphigoid. The BIOCHIP has demonstrated itself to be a specific test for BP180 (96.5-100%) and BP230 (98.3-100%), with a high sensitivity for BP180 (83.3-100%) but poor sensitivity for BP230 (24.3-66.7%). The BIOCHIP mosaic-based immunofluorescence test is potentially a simple, time-and effort-saving test that can aid in the diagnosis and screening of bullous pemphigoid.Further studies should report on the inter-rater reliability of the BIOCHIP to further validate the tool.