Figure 2. Determination and frequency of antibodies to NMDAR and uncharacterized cell-surface antigens in a retrospective cohort of patients with HSE.

A: HEK cells expressing GluN1/GluN2 subunits of the NMDAR incubated with CSF of the indicated patients (left column, green fluorescence), and a monoclonal antibody to GluN1 (middle column, red); the merged immunostaining is shown in the right column. Nuclei of neurons demonstrated with DAPI. Scale bar 10μm. Note that only patient #7 had antibodies to NMDAR (a similar staining was obtained with cells transfected only with GluN1, not shown). B and C: Reactivity of the CSF of the same patients with sagittal sections of rat brain (B), and live rat hippocampal neurons (C). The CSF of patient #7 shows a typical pattern of NMDAR reactivity with the neuropil of hippocampus as well as with the cell-surface of neurons; the CSF of patient #8 shows reactivity with a neuropil antigen expressed on the cell-surface of neurons (the identity of the antigen is unknown), and the CSF of patient #37 was negative in both tests. Scale bar in B 500μm; Scale bar in C 10μm.

D: Percentage of patients’ serum and CSF samples harboring IgG antibodies to NMDAR (black) or to other neuronal cell-surface antigens (grey) during and after the first week of HSE; the identity of other neuronal antigens was unknown. Frequency increased over time (serum p=0.004, CSF p=0.04, Mann Whitney U test).