Evaluation of commercially available ELISA assays as a tool for monitoring and managing pemphigus patients: a prospective study

Background: Pemphigus is a potentially life-threatening auto-immune blistering disease and consequently it is important to monitor disease activity. Objectives: To assess the usefulness of serial antibody titers in the management of pemphigus and to predict disease activity in the clinical follow-up of pemphigus patients. Materials and methods: In this prospective observational study, seven patients with pemphigus vulgaris and three patients with pemphigus foliaceus were examined on a monthly basis for 24 months, or two-weekly during active disease. Disease activity was registered according to a new score system. Results: A total of 158 samples were tested using commercial desmoglein (Dsg) 1 and Dsg3 enzyme-linked immunosorbent assay (ELISA) kits. The 20 U/mL cut-off for the anti-Dsg1 ELISA value was associated with a significantly higher risk of a skin activity score >0 (OR = 7.91, 95% CI = 1.71; 36.65, p = 0.01). A cut-off for disease activity at 5 gave an OR of 11.40 (95% CI = 2.64; 49.09, p = 0.003). Dsg1 values of > 15 had a sensitivity of 79.41% and specificity of 87.80% for predicting a relapse of skin disease in pemphigus patients. For Dsg3, no odds could be calculated for mucosal involvement, nor a predicting value for mucosal relapse. Conclusion: We conclude that only Anti-Dsg1 antibody ELISA values seem valuable in the follow-up of pemphigus patients and carry a predictive value. However, serial antibody titers cannot be seen as absolute indicators of disease activity and we believe that both Dsg1 and Dsg3 ELISA tests should be used with caution to monitor disease activity