A Probing of the Issue of Detecting IgG, IgG4 and IgA Antibodies to Laminin 332 Epitopes in Mucous Membrane Pemphigoid: A Clinical-Laboratory Experience of a Single Central European University Dermatology Department

Abstract

Purpose Mucous membrane pemphigoid (MMP) is a very rare autoimmune bullous disease, affecting predominantly the mucosae and characterized by autoantibodies to the epithelial basement membrane components. Laminin 332 (Ln-332) is one of the most probable antigens with association with malignancy. The laboratory diagnosis of Ln-332-mediated autoimmunity is troublesome. The aim here was to comparatively examine IgG, IgG4, and IgA autoantibodies specific to α3, β3 or γ2 subunits of Ln-322 in MMP patients using the BIOCHIP mosaic-based indirect immunofluorescence technique (IIF). Patients and Methods Sera from 15 MMP patients were studied. BIOCHIP mosaic-based Ln-332 IIF, direct immunofluorescence, ELISA tests for anti-BP180/BP20 IgG antibodies and statistical analyses were performed. Results Of all the 15 sera examined for IgG4 antibodies, only 1 (6.67%) reacted with the α3 chain, 0 with the β3 chain, and 0 with the γ2 chain. No positive reactivity was seen with the IgG and IgA antibodies. BIOCHIP mosaic-based IIF with Ln-332 showed 100% sensitivity, 8% specificity, 21% positive predictive value, and 100% negative predictive value in relation to the diagnostic gold standard of DIF. The concomitant malignancies were revealed in three cases. Conclusion The detection of antibodies to Ln-332 chains is occasional in Polish MMP sufferers. Still, the evaluation of IgG4 antibodies in MMP can reduce the false-negative results.

Autoimmunity against laminin 332

“…When in an international multicenter study, 93 anti-laminin 332 MMP patient sera and 315 sera from other autoimmune blistering diseases including 153 sera from anti-laminin 332 negative MMP patients, non-inflammatory dermatoses, and heathy blood donors were probed, a sensitivity of 84% and a specificity of 99.6% were observed ( 38 ). This assay has subsequently been validated by other groups ( 66 , 67 ). When the BIOCHIP ® technology-based assay has recently been compared with the footprint assay using 54 anti-laminin 332 MMP sera and together 50 sera from patients with pemphigus vulgaris and healthy blood donors, both assays revealed a specificity of 100% with a slightly higher sensitivity of the footprint assay (100% versus 96.3%) ( 60 ).…”