PEMPHIGUS SERA RECOGNIZE CONFORMATIONALLY SENSITIVE EPITOPES IN THE AMINO-TERMINAL REGION OF DESMOGLEIN-1

To identify regions of the Desmoglein-1 (Dsg1) extracellular domain th at are targeted by pemphigus antisera, cDNA sequences encoding various regions of the Dsg1 extracellular domain were ligated to sequences en coding the E-cadherin extracellular anchor and transmembrane and cytop lasmic domains, These constructs were then expressed in mammalian cell s, and pemphigus sera were tested for the ability to recognize the Dsg 1. extracellular domains. When analyzed by immunoblot, very few pemphi gus foliaceus sera recognized the Dsg1 domains, To determine whether p emphigus sera recognize non-denatured Dsg1 domains, constructs were ex pressed in cultured cells and tested for reactivity with pemphigus ser a using live-cell immunofluorescence. The pemphigus foliaceus sera rea cted strongly with the Dsg1 extracellular domain by live-cell immunofl uorescence and recognized predominantly the aminoterminal region of th e Dsg1 extracellular domain, In addition, sera from patients with pemp higus vulgaris also demonstrated strong reactivity with the Dsg1 extra cellular domain when tested using live-cell immunofluorescence. In con trast, sera from normal human controls and sera from bullous pemphigoi d patients did not react with the Dsg1 extracellular domain, These dat a indicate that both pemphigus foliaceus and pemphigus vulgaris sera r eact with conformationally sensitive epitopes in the amino-terminal re gion of Dsg1.