Impact of adding an IgG4 conjugate to routine direct immunofluorescence testing for subepithelial and intraepithelial autoimmune blistering disorders.

IgG4 allowed for classification of over 40% of cases that were otherwise equivocal by IgG and C3. IgG4 staining showed lower levels of non-specific background staining than did IgG or C3. IgG4 appears to contribute the most value in cases with cell-surface deposition and with equivocal linear IgG deposition and negative C3 results. This article is protected by copyright. All rights reserved.