Factors Affecting the Results of Direct Immunofluorescence in Patients with Bullous Pemphigoid

Seo, Ji Young; Lee, Ho Yeol; Woo, Cheong Ha; Choi, Mira; Haw, Sik; Kim, Han Seong; Park, Hai Jin

Abstract

BACKGROUND
The diagnosis of bullous pemphigoid is made based on clinical, histologic, and immunofluorescence features.
OBJECTIVE
The purpose of this study was to analyze the factors that may affect the positivity and intensity of direct immunofluorescence (DIF) in patients with bullous pemphigoid.
METHODS
We performed a retrospective review of 41 cases of bullous pemphigoid at Ilsan Paik Hospital between January 2008 and December 2014. We investigated the positivity of DIF, immunofluorescence intensity of C3, age, sex, biopsy sites, extent of disease, duration of disease, and the degree of inflammatory cell infiltration.
RESULTS
Twenty-seven of 41 (65.9%) cases had positive DIF results for either IgG or C3, and 14 of 41 (34.1%) had negative DIF results for both IgG and C3. Twenty-one cases (51.2%) of IgG and 25 cases (61.0%) of C3 had characteristic linear C3 deposition on the dermo-epidermal junction. Disease duration influenced DIF positivity (p<0.05). Although a higher positive rate of DIF was observed in biopsy specimens taken from the upper extremities than in those from other sites, the difference was not statistically significant. Sex, age, extent of disease, and the degree of inflammatory cell infiltration were not significantly associated with the positivity of DIF. There was no relationship between fluorescence intensity of C3 and the degree of inflammatory cell infiltration.
CONCLUSION
This study suggests that the long duration of disease (more than 10 days) may increase the positivity of DIF. Age, sex, biopsy site, extent of disease, and the degree of inflammatory cell infiltration had no influence on DIF positivity.