Pemphigus is an autoimmune blistering disease caused by
immunoglobulin (Ig)G
autoantibodies against
desmogleins (Dsg). In mucosal-dominant
pemphigus vulgaris (PV), anti-Dsg3
antibodies play a critical role in
acantholysis. We followed two mucosal-dominant PV cases who suffered from refractory oral mucosal erosions. In these cases, anti-Dsg3 serum
antibodies were not detected by indirect immunofluorescence and
enzyme-linked
immunosorbent assay (ELISA). However, direct immunofluorescence showed the intercellular
IgG deposition in the epidermis and histopathological findings revealed suprabasal
acantholysis. In order to analyze the pathomechanisms in these cases, we first examined the Dsg3 expression patterns in lesional sites and compared them with those of typical mucosal-dominant PV cases. In typical PV cases, the alteration of Dsg3 distribution was observed in lesional sites by immunostaining. The aggregation of Dsg3, which is the characteristic change in PV mucosal lesions, was observed as the initial change prior to
acantholysis. In our cases, a clustering of Dsg3 was observed at mucosal lesions, and the expression levels of Dsg3 in acantholytic lesions were decreased, as observed in typical mucosal-dominant PV cases. Although anti-Dsg3 serum
antibodies could not be detected by routine tests, anti-Dsg3 serum
antibodies were detected by Dsg3 ELISA using 10-times more concentrated sera (highly sensitive ELISA). Moreover, purified and concentrated PV
IgG showed high pathogenicity when examined by dissociation assay. In conclusion, the detection of morphological changes in Dsg3 distribution and highly sensitive ELISA method could be useful for the early diagnosis of PV recurrence.