This first systematic screening study of various NAbs showed 22.5% seropositivity belonging mostly to VGKC-complex antibodies in a large consecutive series of patients with MTLE-HS. Our results indicated a VGKC-complex autoimmunity-related subgroup in the syndrome of MTLE-HS.

Autonomic dysfunction has frequently been reported in autoimmune encephalitis associated with seizures and there is growing evidence that epilepsy patients may display neuronal autoantibodies (NAAb). The aim of this study was to investigate the frequency of NAAb in epilepsy patients with peri-ictal autonomic findings. Fifty-eight patients (37 women/21 men; average age of 34.2 ± 9.9 years and epilepsy duration of 19.1 ± 9.6 years) who had at least one video-EEG recorded focal or secondary generalized seizure with clear-cut documented peri-ictal autonomic findings, or consistently reported seizures with autonomic semiology, were included. NAAb were tested by RIA or cell based assays. NAAb were present in 17 of 58 (29.3%) patients. Among seropositive patients, antibodies were directed against N-methyl-D-aspartate receptor (NMDAR) in 5 (29%), contactin-associated protein-like 2 (CASPR2) in 5 (29%), uncharacterized voltage gated potassium channel (VGKC)-complex antigens in 3 (18%), glutamic acid decarboxylase (GAD) in 2 (12%), glycine receptor (GLYR) in one (6%) and type A gamma aminobutyric acid receptor (GABAAR) in one patient (6%). Peri-ictal gastrointestinal manifestations, piloerection, ictal fever, urinary urge, and cough occurred more commonly in the seropositive group. The prevalences of psychotic attacks and status epilepticus were significantly increased in the seropositive group. Seropositivity prevalence in our patient group with peri-ictal autonomic findings is higher than other previously reported epilepsy cohorts. In our study, ictal fever-VGKC-complex antibody and pilomotor seizure-GABAAR antibody associations were documented for the first time. Chronic epilepsy patients with peri-ictal autonomic semiology, history of status epilepticus and psychotic disorder may benefit from autoantibody screening.

Our results support the notion that ion channel autoimmunity might at least partially contribute to HaNDL pathogenesis and occurrence of neurological symptoms.

Thy-Abs can be found in a high proportion of patients with non-paraneoplastic LE, often in association with antibodies to specific or as yet undefined neuronal surface antigens. These results suggest that acute idiopathic encephalitis patients with Thy-Abs should be closely monitored for ion-channel antibodies and it should not be assumed that they have HE.

No disease-specific neuronal antibodies have so far been defined in neuro-Behçet's disease (NBD). Immunohistochemistry and immunocytochemistry studies showed antibodies to hippocampal and cerebellar molecular layers and the surface antigens of cultured hippocampal neurons in sera and/or cerebrospinal fluids (CSF) of 13 of 20 NBD and 6 of 20 BD patients but not in multiple sclerosis or headache controls. Screening with a protein macroarray led to identification of stress-induced-phosphoprotein-1 (STIP-1) as an antigenic target. High-titer STIP-1-antibodies were detected in 6 NBD patients' sera but not in controls. These results suggest that neuronal antibodies could be useful as diagnostic biomarkers in NBD.