Fig 4.

Patients’ antibodies react with heteromers of NR2B and NR2A subunits of the N-methyl-D-aspartate receptor (NMDAR). HEK293 cells expressing heteromers (NR1/NR2B or NR1/NR2A) or transfected with single subunits NR1 or NR2B of the NMDAR were incubated with patients’ serum or cerebrospinal fluid (CSF). (top row) Panels demonstrate that the CSF of Patient 7 reacts with cells expressing heteromers (functional receptors) of NR1/NR2B and NR1/NR2A, but not with cells transfected with single subunits (NR1; NR2B). Cells transfected with single NR2A or plasmid without insert were not reactive with patient’s antibodies (not shown). (bottom row) Panels demonstrate the reactivity of the CSF of Patients 1 and 3 with NR1/NR2B. In the third panel (#7 + NR2B), the cells were coincubated with CSF of Patient 7 and an antibody specific for NR2B, showing colocalization of reactivities. The fourth panel (C (−)) corresponds to the CSF of an individual without paraneoplastic encephalitis (negative control). Original magnification ×800, immunofluorescence; nuclei of cells demonstrated with 4′,6-diamidino-2-phenylindole (DAPI), except “#7 + NR2B,” in which no DAPI was used.