Detection of Acetylcholine Receptor Blocking Antibodies by Flow Cytometry.

OBJECTIVES Detection of acetylcholine receptor (AChR) blocking antibodies through the use of a radiolabel has become standard procedure in most laboratories. Known drawbacks associated with radioassay, including cost of radioisotopes, hazards to laboratory professionals, and manufacture and disposal of radioactive materials, have prompted investigation into replacement assays. We describe here a high-throughput immunofluorescent flow cytometric assay designed for the detection of AChR blocking antibodies. METHODS In total, 323 serum samples were tested on both the AChR blocking radioassay and the new immunofluorescent flow cytometric assay. RESULTS Analysis of the results revealed a 96.9% concordance between the two assay methods. CONCLUSIONS Our results indicate that a new immunofluorescent flow cytometric AChR blocking antibody assay is not only feasible but clinically comparable in both sensitivity (91%) and specificity (99%) compared with radioassay.