USE OF RECOMBINANT PEMPHIGUS-VULGARIS ANTIGEN IN DEVELOPMENT OF ELISAAND IB ASSAYS TO DETECT PEMPHIGUS-VULGARIS AUTOANTIBODIES

Aim/Objective The objectives of this Study are: (1) to measure the tit ers of pemphigus vulgaris (PV) autoantibody in the sera of patients wi th active disease, using-three different assays: (a) Indirect immunofl uorescence (IIF) using monkey esophagus as a substrate, ih) immunoblot (IB) and, (ci enzyme-linked immunosorbent assay (ELISA) using recombi nant PV antigen (rPVA). (2) To compare the sensitivity of: these three assays. Background The titer of PV autoantibodies and disease severit y and extent do not always correlate. This could be due to the lack of consistency and specificity of the substrate, Different results are o btained using different substrates. A standard substrate with uniforml y controlled source of antigen would be more useful and clinically ben eficial. Methods In this study we studied 25 PV patients, six each wit h bullous pemphigoid (BP), ocular cicatricial pemphigoid (OCP), mucous membrane pemphigoid (MMP), and herpes gestationis (HG), and sera from 16 normal subjects, IIF was used to determine the PV autoantibody usi ng monkey esophagus. IB assay was used according to standard protocol using normal human epidermis and rPVA as substrates, ELISA was perform ed using rPVA as antigens expressed in E. coli. Results Sera of all 25 PV patients showed binding to the rPVA, normal human sera and the ser a from the six BP, six OCP, six MMP, and six I-ic patients did nor sho w any binding. In addition, we used antisera from rabbits immunized wi th PVA peptides (Bos-1, Bos-6) which also showed binding to rPVA, wher eas normal rabbit sera did not show any reactivity. ELISA and IB titer s in all the patients were 2.5 to 160 times higher than with the conve ntionally used IIF assay. The liters of the PV specific autoantibody m easured using the rPVA did not show statistically significant differen ces between the ELISA and IB assays. Conclusions IB and ELISA are supe rior to IIF in evaluating the antibody levels in PV patients. ELISA is more practical and is preferable to IB and is recommended for clinica l use. (C) 1998 Elsevier Science B.V.