Comparison of enzyme-linked immunosorbent assay test with immunoblot assay in the diagnosis of pemphigus in Indian patients

Background: The diagnosis of pemphigus vulgaris (PV) and pemphigus foliaceous (PF) rests upon clinical, histological and immunofluorescence features. Enzyme-linked immunosorbent assay (ELISA) test and immunoblot (IB) assay have shown variable sensitivity and specificity. Aims: We compared the utility of ELISA and IB in pemphigus patients. Methods: Sixty-six pemphigus cases (PV-54, PF-12) and 72 controls (other vesicobullous disorders and healthy controls) were inducted. ELISA for anti-Dsg 3 and 1 antibodies and IB assay were performed. Results: On ELISA, both mean anti-Dsg 1 and 3 titers were raised in PV and PF. Mean anti-Dsg 1 in mucocutaneous PV was significantly higher than in mucosal PV and mean anti-Dsg 3 was significantly raised in PV than in PF. Anti-Dsg 1 and 3 in the control group were negative. Sensitivity and specificity of ELISA in PV was 98.14% and 90.5% while in PF it was 91.6% and 61.1%, respectively.On IB in PV, 36 cases (66.67%) showed the 130 kDa and 160 kDa antigen bands, 12 (22.2%) only the 130 kDa and six (11.1%) only the 160 kDa band. Eight of the nine pure mucosal cases (88.8%) showed only the 130 kDa. In PF, only the 160 kDa antigen was detected. These antigens were not identified in the control group. Sensitivity and specificity of IB in PV was 88.9% and 100% and in PF it was 100% and 95.2%, respectively. Conclusion: Both tests could differentiate pemphigus from other dermatoses, including other blistering disorders. ELISA could not make a distinction between PV and PF or between the various clinical phenotypes of PV. IB differentiated between PV and PF and the different clinical variants of PV