Fig. 1.

NMDAR1-AB seropositivity and functionality across mammalian species. a Cross-validation of assays: paired serum and intraventricular CSF samples from neurosurgical patients were tested using a HEK293T cell-based clinical standard assay for NMDAR1-AB seropositivity (Euroimmun biochip). For step 1, fluorescently labeled IgA-specific, IgM-specific, and IgG-specific secondary AB were used; for method cross-validation (step 2), NMDAR1-AB seropositive and seronegative samples of each Ig class from step 1 were labeled with protein-A–FITC conjugate and tested for colocalization (yellow) of protein-A–FITC⁺ (green) and M68⁺ (monoclonal mouse NMDAR1-AB followed by Alexa555 donkey anti-mouse IgG red). Representative pictures of both methods using the same seropositive samples (IgA, IgM, and IgG) are displayed on the right: upper row step 1/lower row step 2. b NMDAR-AB seropositivity (%) of young and old mammals for all Ig classes combined (^#protein-A–FITC/Euroimmun) or for individual classes (⁺Euroimmun; *protein-A–FITC/Euroimmun and cross-validation with Euroimmun/monkey IgM) presented in the bars; color codes used for consistency and kept also in c and d; age given in months (m) or years (y); χ² or Fisher’s exact test. c NMDAR-AB seropositivity of subjects with migration (first and second generation) vs. nonmigration history (GRAS data collection); all Ig classes presented; age split at 35 years; χ² test. d NMDAR1-AB course by Ig classes in serum over age groups in migrants vs. nonmigrants of the extended GRAS data collection. Note the different course particularly for IgA. eFunctionality testing of NMDAR1-AB in human IPSC-derived cortical neurons: degree of internalization expressed as a ratio of fluorescence intensity measured at 37 and 4 °C; number of neurons and sera (N) given; Mann–Whitney U test