Recombinant desmoglein 3 has the necessary epitopes to adsorb and induce blister-causing antibodies

Abstract

The development of an animal model for studying the pathogenesis of pemphigus vulgaris (PV) has been hampered by the unavailability of the purified full-length autoantigen desmoglein 3 (Dsg 3). Therefore, we expressed Dsg 3 using a baculovirus expression system. The expressed protein was identified as Dsg 3 by its reactivity with a pan-cadherin anti-serum, an anti-serum to a Dsg 3 synthetic peptide, or patient serum, and by amino-terminal sequencing. Carbohydrate analysis showed that recombinant Dsg 3 was glycosylated. While a majority of the recombinant protein was cell associated, by immunoprecipitation, some Dsg 3 was demonstrated in the medium. The Dsg 3 could adsorb out blister-causing antibodies from patient sera. Rabbit anti-Dsg 3 antibodies induced by the recombinant Dsg 3 showed specific binding to intercellular spaces of monkey esophagus by indirect immunofluorescence. Moreover, these antibodies induced PV-like blisters in neonatal mice and weakly bound perilesional epidermis. Availability of large quantities of relatively pure Dsg 3 should now facilitate studies aimed at understanding Dsg 3 structure and pathogenesis of PV, with implications for developing specific immunotherapies.