The use of BIOCHIP technique in diagnosis of different types of pemphigus: Vulgaris and foliaceus

Background: Pemphigus is a rare, autoimmune blistering disease characterized by autoantibodies against desmoglein 3 (Dsg3) and 1 (Dsg1) with mucosal and/or skin involvement. Main types of pemphigus include mucosal pemphigus vulgaris (m-PV), mucocutaneus pemphigus vulgaris (mc-PV) and pemphigus foliaceus (PF) determined by clinical picture, positive direct and indirect immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Methods: We evaluated the sensitivity and specificity of a novel multi-substrate immunofluorescence technique called BIOCHIP in the diagnosis of main types of pemphigus. Additionally, we tested agreement between BIOCHIP-Dsgl and ELISA-Dsgl in differentiation pemphigus vulgaris subtypes. The study comprised 35 patients with pemphigus: 14 patients with PF, 21 with PV (13 with mPV and 8 with me-PV) and 48 controls. Results: The intercellular staining on monkey esophagus substrate in BIOCHIP was observed in 23/35 pemphigus in total (sensitivity 65.7%), 17/21 PV (sensitivity 81.0%), 10/13 m-PV (sensitivity 76,9%), 7/8 me-PV (sensitivity 87.5%) and 6/14 PF (sensitivity 42.9%), but not in 48 controls. Dsg3 positive staining in BIOCHIP was observed in 21/21 PV (sensitivity 100%), 13/13 m-PV (sensitivity 100%), 8/8 me-PV (sensitivity 100%), whereas Dsg3 was negative in all 14 PF sera. Dsg1 reactivity was detected in 9/21 PV (sensitivity 42.8%), 2/13 m-PV (sensitivity 15,4%), 7/8 me-PV (sensitivity 87.5%) and 13/14 PF (sensitivity 92.9%). All 48 controls were negative for both Dsg3 and Dsg1. An excellent agreement for BIOCHIP-Dsg1 and ELISA-Dsg1 for m-PV and mc-PV was found, which reflect k values of 1.0 and 0.91, respectively. Conclusion: BIOCHIP technique is a useful method for pemphigus diagnostics and differentiation between its subtypes: m-PV, me-PV and PF.