Supplementary Material for: Comparison of a Novel Homogeneous Cyclic Amp Assay and a Luciferase Assay for Measuring Stimulating Thyrotropin-Receptor Autoantibodies

Objective: Stimulating thyrotropin-receptor antibodies (TSAb) cause Graves’ disease (GD). We tested a novel homogeneous fluorescent 3′,5′ cyclic adenine monophosphate (cAMP) assay for the detection of TSAb in a bioassay. Methods: Chinese hamster ovary (CHO) cell lines expressing either a chimeric (MC4) or wild-type (WT) TSH-R were incubated with the adenyl cyclase activator forskolin, a human TSAb monoclonal antibody (M22), and with sera from GD patients. Intracellular cAMP levels were measured using a Bridge-It® cAMP assay, and the results were compared with a luciferase-based bioassay. Results: Both cell lines were stimulated with forskolin concentrations (0.006–200 µM) in a dose-dependent manner. The linear range in the MC4 and WT cells was 0.8–25 and 3.1–50 µM, respectively. Levels of cAMP and luciferase in forskolin-treated MC4 and WT cells were positively correlated (r = 0.91 and 0.84, both p r = 0.88, p p = 0.002). A positive correlation was also noted when using patient samples (r = 0.96, p Conclusion: The novel, rapid, simple-to-perform cAMP assay provides TSAb-mediated stimulatory results comparable to a luciferase-based bioassay.