Study Antigen targets Methodology Conventional diagnostic methods Diagnostic accuracy metrics Clinical utility Summary of main results Improvements in diagnostic accuracy or clinical decision-making
Zhou et al. [28] Desmoglein 1
and Desmoglein 3
(by ELISA) 		IIF, ELISA, Tzanck smear test Histopathology,
DIF 		Sensitivity and specificity for IIF, ELISA, Tzanck smear, and serial testing Tzanck smear and ELISA serial testing recommended as a simple, rapid and reliable way to diagnose pemphigus in dental clinics Sensitivities: Tzanck smear 96.7%, IIF 84.8%, ELISA 84.8%;
specificities: Tzanck smear 60%, IIF 91.8%, ELISA 96.7%;
serial testing of Tzanck smear and ELISA showed 82% sensitivity, 98.7% specificity 		Serial testing of Tzanck smear and ELISA recommended as a simple, rapid and reliable diagnostic approach for pemphigus in dental clinics
Masquijo-Bisio et al. [29] Fibrinogen deposition
at BMZ 		Immunofluorescence staining of
biopsy samples 		Clinical examination, histopathological analysis Not reported Differentiating plaque-type OLP from homogenous leukoplakia when clinical and histopathological features are ambiguous Fibrinogen deposition at the BMZ was detected in 100% of plaque-type OLP cases, but in 0% of homogenous leukoplakia cases DIF using anti-fibrinogen antibody can improve diagnostic accuracy when differentiating plaque-type OLP from homogenous leukoplakia
Yamanaka et al. [30] BMZ, Civatte bodies
(apoptotic cells) 		Patients with OLP and OLL were compared to patients with MMP, PV,
and fibrous hyperplasia 		Clinical and histopathological features Frequency of positive DIF in OLP (73.3%) and OLL (38.4%) DIF is a key tool in differentiating some lichenoid lesions and could improve the diagnosis of OLP and OLL, especially in lesions showing typical clinical and histological features of OLP 22 patients with OLP (73.3%), 10 with OLL (38.4%), 25 with MMP (96.1%), and all with PV (100%) had positive DIF. The most frequent DIF pattern was linear fibrinogen at the BMZ. A logistic regression model found a statistically significant difference in positive DIF between OLP and OLL DIF can improve the diagnosis of OLP and OLL, especially in lesions with typical clinical and histological features of OLP
Abdalla et al. [31] E-cadherin, EMP1, 5T4, N-cadherin Quantitative IF microscopy to assess marker expression in tissue samples Not specified Z-scores calculated to predict abnormal epithelium and classify disease grades (LGD, HGD, T1 OSCC, T4 OSCC) Markers (E-cadherin, EMP1, N-cadherin) can predict abnormal epithelium and classify disease grades Loss of E-cadherin is an early event in oral dysplasia. Loss of E-cadherin and EMP1 is an indicator of LGD.
Loss of E-cadherin, EMP1 and 5T4 is an indicator of HGD.
Expression patterns of E-cadherin, EMP1 and N-cadherin can predict abnormal epithelium and classify disease grades.
Significant differences in marker expression observed in safety margins compared to normal tissue 		Provides a quantitative, objective approach to assess epithelial markers that can improve diagnosis and classification of oral dysplasia and OSCC
Kamaguchi et al. [32] BMZ proteins Biopsy of non-lesional buccal mucosa, DIF analysis Histological analysis, IIF, ELISA, immunoblotting DIF of non-lesional buccal mucosa was positive in all 7 cases, while conventional methods failed to detect autoantibodies in any of the cases DIF using non-lesional buccal mucosa was superior to histological and serological tests for diagnosing MMP DIF using non-lesional buccal mucosa was able to detect linear deposits of IgG and C3 at the BMZ in all 7 MMP cases, while conventional diagnostic methods failed to detect autoantibodies.
This procedure was found to be technically easy and have high diagnostic value 		DIF using non-lesional buccal mucosa improved diagnostic accuracy compared to conventional diagnostic methods for MMP.
This could lead to faster diagnosis and initiation of appropriate treatment
Bresler et al. [33] Not specified Patients underwent biopsies for concurrent routine histologic evaluation and DIF testing Routine histology Sensitivity: 0.810,
specificity: 0.989,
negative
predictive value: 0.889,
positive
predictive value: 0.979 		In patients with low clinical suspicion for oral autoimmune bullous disorder, routine histology alone may be sufficient and more cost-effective 57 out of 121 (47.1%) high suspicion cases were consistent with oral autoimmune bullous disorder on DIF.
11 cases in the high suspicion group were histologic false negatives.
No histologic false negatives or inconclusive DIF results in the low suspicion group 		Routine histology alone may be sufficient in low clinical suspicion cases, avoiding the need for more expensive DIF testing
Reyes et al. [34] Components of the β-catenin destruction complex, early endosome markers Tissue IF, cell culture experiments with DOK and non-dysplastic oral keratinocytes (OKF6), Rab5 activity assays, subcellular fractionation, transcription and protease protection assays Histological assessment of oral dysplasia Not reported Understanding the mechanisms underlying nuclear accumulation of β-catenin in oral dysplasia, which is associated with progression to OSCC Increased Rab5 activity and endosomal sequestration of the β-catenin destruction complex leads to stabilization and nuclear accumulation of β-catenin in oral dysplasia This study provides insights into the molecular mechanisms involved in the progression of oral dysplasia, but does not directly report improvements in diagnostic accuracy or clinical decision-making
Tikkhanarak et al. [35] BMZ, cytoid/CBs DIF analysis to evaluate immunoreactant patterns Medical history, oral examination, histopathology Not explicitly reported DIF interpretation can aid in differentiating OLP, OLP/LE, chronic ulcerative-like lesion, immune-mediated disease, or dysplasia Atrophic pattern was most common in OLP, OLL, and OLDR groups. DIF confirmed OLP in only 41.2% of OLP cases, with 23.5% each as LP/LE or negative.
In OLL, most common DIF was LP/LE or non-specific (31.6% each). In OLDR, DIF was OLP, LP/LE, immune complex-mediated disease, or mixed connective tissue disease.
1 OLDR case showed mild to moderate dysplasia. No significant differences in ANA positivity or patterns between groups 		DIF analysis can aid in differentiating OLP, OLL, and OLDR, identifying cases that may not be typical OLP or OLL

ACIF = anticomplement immunofluorescence; ANA = antinuclear antibody; BMZ = basement membrane zone; C3 = complement component 3; CB = cytoid bodies; DIF = direct immunofluorescence; DG = desquamative gingivitis; Dsg1 = desmoglein 1; Dsg3 = desmoglein 3; H&E = hematoxylin and eosin; HGD = high-grade dysplasia; IIF = indirect immunofluorescence; IgG = immunoglobulin G; IgA = immunoglobulin A; IgM = immunoglobulin M; LE = lupus erythematosus; LGD = low-grade dysplasia; MMP = mucous membrane pemphigoid; MMO = maximum mouth opening; OLDR = oral lichenoid dysplasia; OLL = oral lichenoid lesions; OLP = oral lichen planus; OMLP = oral mucosal lichen planus; OSCC = oral squamous cell carcinoma; OSF = oral submucous fibrosis; PV = pemphigus vulgaris; RAS = recurrent aphthous stomatitis; T1 = tumour size classification (smallest); T4 = tumour size classification (largest); ELISA = enzyme-linked immunosorbent assay; HCV = hepatitis C virus; SCC = squamous cell carcinoma; IF = immunofluorescence.