Multicenter prospective study on multivariant diagnostics of autoimmune bullous dermatoses using the BIOCHIPTM Technology

Stine Krüger1, Tarek Fuhrmann1, Nina van Beek1, Lars Komorowski2, Kai Fechner1, Detlef Zillikens1, Winfried Stöcker2, Enno Schmidt1, Kristin Rentzsch2 and the International Autoimmune Bullous Diseases Study Group*
1Department of Dermatology, University of Lübeck, Lübeck
2Institute of Experimental Immunology, Euroimmun AG, Lübeck
*International Autoimmune Bullous Diseases Study Group: Giovanni Di Zenzo (Rome, Italy), Marian Dmochowski (Poznan, Poland), Kossara Drenovska (Sofia, Bulgaria), Hilayda Güngör (Ankara, Turkey), Michael Horn (Bern, Switzerland), Hana Jedlickova (Brno, Czech Republic), Cezary Kowalewski (Warsaw, Poland), Branka Marinovic (Zagreb, Croatia),  Ljiljana Medenica (Belgrade, Serbia), Dedee Murrell (Sydney, Australia), Aikaterini Patsatsi (Thessaloniki, Greece), Eli Sprecher (Tel Aviv, Israel), Soner Uzun (Antalya, Turkey), Snejina Vassileva (Sofia, Bulgaria), Xuejun Zhu (Beijing, China)

Although direct immunofluorescence (IF) microscopy is still the gold standard for the diagnosis of autoimmune bullous diseases (AIBDs), serological diagnosis made by different antigen-specific assays is possible in the majority of patients. Here, the feasibility of a newly designed extended mosaic using the BIOCHIPTM technology is explored. By combining multiple substrates for indirect IF microscopy in a single incubation field, the current BIOCHIPTM mosaic allows simultaneous testing on tissue substrates (primate oesophagus, primate salt-split skin, rat bladder, monkey liver), antigen expressing HEK293 cells (desmoglein 1, desmoglein 3, type VII collagen, BP230 C-terminus) and recombinant proteins (BP180 NC16A, gliadin GAF3x) and is compared to the stepwise routine diagnostic. In this study, 749 patients with AIBDs with positive direct IF (DIF) microscopy were included. Sera were taken at the time of diagnosis and analyzed independently by both the stepwise routine diagnostic algorithm and BIOCHIPTM technology. 
A high correlation was found between the BIOCHIPTM mosaic, the routine diagnostic algorithm, and the results of DIF microscopy classifying patients as pemphigoid or pemphigus. For the detailed diagnoses established by BIOCHIPTM mosaic and routine stepwise analysis, Cohens κ ranged from 0.84 to 1.00 for pemphigus vulgaris, pemphigus foliaceus, paraneoplastic pemphigus, bullous pemphigoid, dermatitis herpetiformis, linear IgA disease, and epidermolysis bullosa acquisita. Divergent results occurred in 124 of 749 sera (16.5%) of which 58 (7.7%) led to different diagnoses. Out of these, 21 diverging diagnoses can be explained by lack of certain target antigens, e.g. laminin 332 or laminin gamma1/ p200-protein in the BIOCHIPTM mosaic. In conclusion, the evaluated BIOCHIPTM mosaic showed a high correlation with the established diagnostic algorithm and is a faster and easy to apply alternative for the diagnosis of both IgG- and IgA-mediated AIBD.

Multicenter prospective study on multivariant diagnostics of autoimmune bullous dermatoses using the BIOCHIPTM technology