Figure 2.

Three patients in the AES spectrum were identified based on the live CBA as being positive for serum antibodies against nAChR α4 subunit epitopes. HEK293 cells expressing α4β2, α3β2, α7-nAChRs, or control AQP4 were incubated with sera derived from patients suspected for AES and found to be positive by the live α4β2-nAChR CBA, followed by secondary and third antibodies. Serum anti-nAChR α4 subunit antibodies were identified in a patient with autoimmune meningoencephalomyelitis (A), in a patient with Rasmussen (B), and in a patient with possible autoimmune encephalitis with movement disorder involving stiffness (C). No staining was observed for these patient serum antibodies when targets were α3β2‐ (D‐F) or α7‐nAChRs (G‐I) or AQP4 expressed in transfected cells (J‐L). Double immunostaining was performed in α4β2-transfected HEK293 cells using a monoclonal anti-α4 subunit (mAb299) (M) and positive sera antibodies to α4 subunit of the α4β2-nAChR derived from patients with AES (N). The overlapping immunoreactivity (white arrows) of the mΑb and the positive serum confirmed the specificity of our α4β2-nAChR CBA (O). Scale bar: 20 μm.