Immunofluorescence testing in the diagnosis of autoimmune blistering diseases: overview of 10-year experience.
BACKGROUND
Immunofluorescence testing is an important tool for diagnosing blistering diseases.


OBJECTIVE
To characterize the immunofluorescence findings in patients diagnosed with autoimmune blistering skin diseases.


METHODS
We retrospectively analyzed immunofluorescence results encompassing a 10-year period.


RESULTS
421 patients were included and divided into 2 groups: group 1- intraepidermal blistering diseases (n=277) and 2- subepidermal blistering diseases (n=144). For group 1, positive DIF findings demonstrated: predominance of IgG intercellular staining (ICS) and C3 for pemphigus foliaceus-PF (94% and 73% respectively), pemphigus vulgaris-PV (91.5%-79.5%) and paraneoplastic pemphigus-PNP (66%-33%); ICS IgA in 100% of IgA pemphigus cases, and IgG deposits in the basement membrane zone (BMZ) along with ICS in one Hailey-Hailey patient. The IIF findings revealed mean titers of 1:2.560 for PV and 1:1.280 for PF. For paraneoplastic pemphigus, IIF was positive in 2 out of 3 cases with rat bladder substrate. In group 2, positive DIF findings included multiple deposits at basement membrane zone for epidermolysis bullosa acquisita-EBA (C3-89%,IgG-79%,IgA-47%,IgM-21%) mucous membrane pemphigoid-MMP (C3,IgG,IgA,IgM-80%) and bullous pemphigoid-BP (C3-91%,IgG-39%,IgA-11%,IgM-6%), and IgA at basement membrane zone for IgA linear disease (99%) and dermatitis herpetiformis-DH (dermal papillae in 84.6%). For lichen planus pemphigoides, there was C3 (100%) and IgG (50%) deposition at basement membrane zone. indirect immunofluorescence positive findings revealed basement membrane zone IgG deposits in 46% of BP patients, 50% for EBA, 15% for IgA linear dermatosis and 50% for LPP. Indirect immunofluorescence positive results were higher for BP and EBA with Salt-Split skin substrate.


CONCLUSIONS
Our results confirmed the importance of immunofluorescence assays in diagnosing autoimmune blistering diseases, and higher sensitivity for indirect immunofluorescence when Salt-split skin technique is performed.
Universidade de São Paulo, São Paulo, SP, Brazil.
Samia Trigo
ST
Arbache
Universidade de São Paulo, São Paulo, SP, Brazil.
Tarsila Gasparotto
TG
Nogueira
Universidade de São Paulo, São Paulo, SP, Brazil.
Lívia
L
Delgado
Universidade de São Paulo, São Paulo, SP, Brazil.
Denise
D
Miyamoto
Universidade de São Paulo, São Paulo, SP, Brazil.
Valéria
V
Aoki
D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods*; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012872:Skin Diseases, Vesiculobullous / Q000175:diagnosis* / Q000276:immunology; D012882:Skin Tests
D007070:Immunoglobulin A; D007074:Immunoglobulin G