Preliminary serological studies comparing immunofluorescence assay with radioimmunoassay

We assayed sennn from 12 patients with untreated cicatricial pemphigoid affecting the conjunctiva for circulating autoantibodies directed against the epithelial basament membrane zone. We employed a conventional indirect immunoflourescence assay, with monkey esophagus and human conjunctiva as substrates, and compared the results with those obtained employing a radioimmunoassay measuring antibasement membrane zone antibody binding to COLO-16 and to SCaBER tumor cell lines. The indirect immunofluorescence assay on normal human conjunctival substrate detected circulating antibodies to conjunctival epitheium in 6 of 12 CP patient serum specimens. monkey esophagus failed to detect antibodies to the epithelial basement membrane zone. In contrast, autoantibodies were detected in all 12 specimens by the radioimmunoassay. Spcificity, as demonstrated by appropriate controls and assay of normal human serum, was 100%. These results demonstrate that radioimmunoassay employing COLO-16 or SCaBER cells is an exquisitly sensitive and specific assay for detection of circulating antibasement membrane antibodies in patients with cicatricial pemphigoid affecting the conjunctiva.