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Background: Rituximab is an effective therapy for pemphigus, although relapses are common., Objective: To identify biomarkers to predict relapse of pemphigus following rituximab treatment., Methods: In this retrospective cohort study, 62 patients with pemphigus treated with 99 rituximab cycles provided longitudinal clinical scoring and biomarker data, including levels of CD19 + B cells, CD4 + T cells, and desmoglein 1 (Dsg1) and desmoglein 3 (Dsg3) autoantibodies. An extended time-variant Kaplan-Meier estimator and extended Cox model were applied., Results: Relapse was rare before B-cell repopulation. Univariate analysis revealed low CD4 count (<400 cells/μL) to predict relapse (P < .001). A positive result of testing for Dsg1 (>20 IU) was predictive of relapse among patients with mucocutaneous disease (hazard ratio, 6.40; P = .019); a positive result of testing for Dsg3 (>20 IU) was predictive in patients with mucocutaneous and mucosal disease (hazard ratio, 32.92; P < .001). Multivariable analysis revealed that every CD4 value increase of 200 decreases the hazard ratio for relapse by 35% (P = .029). A positive result of testing for Dsg1 increases the risk for relapse by a factor of 12.32 in patients with mucocutaneous disease (P = .001); positive result of testing for Dsg3 increases risk for relapse by 28.38 in patients with mucosal and mucocutaneous disease (P = .006)., Limitations: Limitations include the retrospective design and inconsistent follow-up., Conclusion: Relapse is associated with B-cell repopulation, low CD4 + T -cell count, and positive result of testing for Dsg1 and Dsg3., (Copyright © 2017 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Serologic diagnosis of autoimmune blistering disease (AIBD) usually follows a sophisticated multistep algorithm., Objective: We sought validation of a multivariant enzyme-linked immunosorbent assay (ELISA) in the routine diagnosis of AIBD., Methods: The multivariant ELISA comprising 6 recombinant immunodominant forms of major AIBD target antigens, ie, desmoglein 1, desmoglein 3, envoplakin, BP180, BP230, and type VII collagen was applied in: (1) a cohort of well-characterized AIBD (n = 173) and control sera (n = 130), (2) a prospective multicenter study with 204 sera from patients with newly diagnosed AIBD with positive direct immunofluorescence microscopy, and (3) a prospective monocenter study with 292 consecutive sera from patients with clinical suspicion of AIBD in comparison with the conventional multistep diagnostic algorithm., Results: Concordant results in the multivariant ELISA compared with direct immunofluorescence microscopy were seen in 94% of patients with pemphigus and 71% of patients with pemphigoid (Cohen κ value, 0.95 and 0.66) and with the conventional multistep diagnostic approach in 91% of patients with pemphigus and 88% of patients with bullous pemphigoid and 93% of autoantibody-negative sera (Cohen κ, 0.95, 0.84, and 0.78)., Limitations: IgA autoantibodies and less common target antigens were not analyzed., Conclusions: The multivariant ELISA is a practical, highly standardized, and widely available novel diagnostic tool for the routine diagnosis of AIBD., (Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)