Comparison of 3 type VII collagen (C7) assays for serologic diagnosis of epidermolysis bullosa acquisita (EBA).

<bold>Background: </bold>Serologic diagnosis of epidermolysis bullosa acquisita (EBA) relies on the detection of circulating autoantibodies to type VII collagen (C7).<bold>Objective: </bold>We sought to compare the diagnostic performances of a commercialized enzyme-linked immunosorbent assay (ELISA) using C7 noncollagenous (NC) domains (C7-NC1/NC2 ELISA) and indirect immunofluorescence (IIF) biochip test on NC1-C7-expressing transfected cells (IIFT), with a full-length-C7 ELISA developed in our laboratory.<bold>Methods: </bold>C7-NC1/NC2 ELISA, IIFT, and full-length-C7 ELISA were run on 77 nonselected consecutive EBA sera.<bold>Results: </bold>C7-NC1/NC2 ELISA, IIFT, and full-length-C7 ELISA were positive, respectively, for: 30%, 27%, and 65% of the 77 sera; 43%, 32%, and 80% of 44 sera labeling the salt-split-skin (SSS) floor (F) by IIF (SSS/F(+)); 9%, 22%, and 47% of 32 SSS/F(-) sera; 28%, 28%, and 58% of classic EBA; 41%, 41%, and 82% of inflammatory EBA; and 18%, 0%, and 55% of mucous-membrane-predominant EBA. Significant differences for all sera were found between: the 2 ELISAs for the 77 sera, SSS/F(+) and SSS/F(-) sera, and IIFT versus full-length-C7 ELISA.<bold>Limitations: </bold>The retrospective design was a limitation.<bold>Conclusion: </bold>C7-NC1/NC2 ELISA and IIFT sensitivities for serologic diagnoses of EBA were low. Full-length-C7 ELISA was significantly more sensitive and could serve as a reference test. [ABSTRACT FROM AUTHOR]