Figure 2. Cell-based assay demonstrating differential binding of AChR antibodies to the adult and fetal receptors.

The fetal (gamma subunit specific) and adult (epsilon subunit specific) forms of the receptors were expressed in human embryonic kidney cells, identified with green fluorescence. Binding of immunoglobulin G was detected by anti-human IgG (red fluorescence). Results of a maternal serum from patient 3 that bound very weakly to the adult receptor (A), but strongly to the fetal receptor (B).