In the case of HSE, autoantibodies are generated in almost one-third of patients; with the majority targeting the NMDA receptor and predominantly IgG1.149,150 NMDAR-specific IgA and IgM antibodies have also been identified in the CSF,134 and chemokines such as CXCL13, CCL19 and a proliferation-inducing ligand (APRIL) were elevated in post-HSE anti-NMDAR AE.45 This phenomenon of immunoglobulin class-switching and chemokine production provides evidence to support the role of germinal centre activity in secondary autoimmunization post-HSE (Box 2). Here, TNFSF13 is linked to Autoimmunity.