2021 年 38 巻 3 号 p. 170-173
The intracellular antigens have been known to involve in several forms of encephalitis/encephalopathy. Anti–Hu and other onco–neuronal autoantibodies against intra–cellular antigens have been identified since 1960s. The autoimmune cerebellar ataxia consists of paraneoplastic ataxia (anti–Yo et al.), anti–GAD–autoantibodies associated ataxia, gluten ataxia (anti–gliadin and TG2) and Hashimoto's encephalopathy (anti–NAE).
Recently, various autoantibodies against antigens in cell surface or inter–synaptic spaces, the NMDA receptor, the AMPA receptor or the VGKC complex (LGI1 and Caspr2) etc., have been also identified in association with several forms of encephalitis/encephalopathy, especially limbic encephalitis. The target antigens are receptors or channels that play crucial roles in synaptic transmission and neural plasticity.
Immuno–precipitation and peptide sequence analysis of the target protein (proteomics) provided the identification of the antigens corresponding to autoantibodies in autoantibody–mediated encephalitis/encephalopathy. Appropriate preparation of antigens (synthesized peptides, or recombinant proteins prepared in E.coli or cultured mammalian cells) and assay systems (immunoblot, ELISA, immunoprecipitation or cell–based assay [CBA]) should be selected for the detection of each autoantibodies.
The early and accurate diagnosis of autoantibody–mediated encephalitis/encephalopathy is important because most patients show responses to immunotherapy. The treatments of autoantibody–mediated encephalitis consist of steroid, immunosuppressants (cyclophosphamide), plasma exchange, intravenous administration of immunoglobulin (IVIg), rituximab and tumor removal. A careful screening of neoplasms is a critical point in both the diagnosis and treatment in autoantibody–mediated encephalitis.
Further studies on the effects of autoantibodies in animal models that recapitulate the disease and the process of recovery, and clinical trials to search for the appropriate treatments are necessary to fully understand autantibody–mediated encephalitis.
