A Novel Simple ImmunoAssay for Quantification of Blood Anti-NMDAR1 Autoantibodies

High titers of anti-NMDAR1 autoantibodies in human brain cause anti-NMDAR1 encephalitis, a rare disease that displays a variety of psychiatric symptoms and neurological symptoms. Currently, immunohistochemical staining and cell-based assays are the standard methods for detection and semi-quantification of the anti-NMDAR1 autoantibodies. Low titers of blood circulating anti-NMDAR1 autoantibodies have been reported in a significant subset of the general human population. However, detection and quantification of these low titers of blood circulating anti-NMDAR1 autoantibodies are problematic because of high non-specific background from less diluted serum/plasma. Development of a new method to quantify these low titers of blood anti-NMDAR1 autoantibodies is necessary to understand their potential impacts on psychiatric symptoms and cognition. Based on our previous One-Step assay, we report the development of a novel simple immunoassay to quantify cross-species blood anti-NMDAR1 autoantibodies, and its validation with immunohistochemistry and cell-based assays in both humans and mice.