title: Brain Infiltration of Immune Cells in CASPR2-Antibody Associated Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis.
abstract: BACKGROUND
  Antibodies directed against neuronal surface antigens have recently been identified in patients with focal temporal lobe epilepsy (TLE) of unknown cause and mesial TLE with hippocampal sclerosis (MTLE-HS), thereby emphasizing the role of autoimmunity in TLE. Antibodies to contactin-associated protein-like 2 (CASPR2) are prevalent in MTLE-HS patients. We aimed to find out whether anti-neuronal autoimmunity might be involved in CASPR2 antibody-related MTLE-HS.
  
  
  METHODS
  Surgically resected medial temporal lobe specimens of seropositive and seronegative MTLE-HS patients were examined with hematoxylin and eosin and immunohistochemical staining using specific immune cell markers.
  
  
  RESULTS
  Two of 5 CASPR2 antibody-positive MTLE-HS patients showed polymorphonuclear and mononuclear cells infiltrating the subarachnoidal region. One of these patients also showed mononuclear cell infiltration in the parenchyma of the temporal lobe cortex. Subarachnoidal and parenchymal infiltrates contained CD3+, CD8+, and CD68+ cells. None of the 13 seronegative MTLE-HS patients displayed cellular infiltrates in their brain samples, and all MTLE-HS patients showed marked neuronal cell loss but no immune cell infiltration in their hippocampi.
  
  
  CONCLUSIONS
  Our results show that CASPR2 antibody-associated MTLE-HS can present with central nervous system inflammation; thus, this subtype of MTLE-HS might have an autoimmune origin.
authors.affiliation: Department of Pathology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Gökçen
authors.initials: G
authors.lastname: Ünverengil
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Ebru Nur
authors.initials: EN
authors.lastname: Vanli Yavuz
authors.affiliation: Department of Neurology, İstanbul University Institute of Experimental Medicine Research, İstanbul, Turkey.
authors.forename: Erdem
authors.initials: E
authors.lastname: Tüzün
authors.affiliation: Department of Neurology, İstanbul University Institute of Experimental Medicine Research, İstanbul, Turkey.
authors.forename: Ece
authors.initials: E
authors.lastname: Erdağ
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Sevil
authors.initials: S
authors.lastname: Kabadayi
authors.affiliation: Department of Pathology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Bilge
authors.initials: B
authors.lastname: Bilgiç
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Betül
authors.initials: B
authors.lastname: Baykan
keywords: Antibody; CASPR2; autoimmunity; hippocampal sclerosis; temporal lobe epilepsy