Detection of acetylcholine receptor modulating antibodies by flow cytometry.

ABSTRACT

OBJECTIVES: To determine the clinical utility and performance characteristics of a laboratory-adapted flow cytometric method for the detection of acetylcholine receptor (AChR) modulating antibodies in myasthenia gravis (MG). METHODS: Serum samples from 120 healthy donors and 100 patients with suspected MG were assessed for the ability to reduce surface AChR concentrations (antigenic modulation) in RD (TE671) or DB40 human muscle cell lines by flow cytometry. Reference ranges were established by receiver operating characteristic curve analysis, and results were then compared with those of the current radioimmunoassay (RIA). RESULTS: Flow cytometric results from the RD cell line had an interpretive threshold of 46% modulation or greater and correlated best (98% sensitivity, 99% specificity) with those of the current RIA. CONCLUSIONS: The new flow cytometric method using the RD cell platform provided higher quality clinical results, a more robust and efficient assay format, a significant cost savings, and less environmental burden.