T cell numbers correlate with neuronal loss rather than with seizure activity in medial temporal lobe epilepsy

Objective Medial temporal lobe epilepsy (MTLE) is a drug-resistant focal that can be caused by broad spectrum of different inciting events, including tumors, febrile seizures, and viral infections. In human surgical resections as well in animal models, an involvement the adaptive immune system was observed. We here analyzed presence T cells various subgroups MTLE. aimed to answer question how much inflammation present whether associated with seizures or hippocampal neurodegeneration. Methods quantified numbers CD3+ CD8+ cytotoxic hippocampus patients gangliogliomas (GGs; intrahippocampal extrahippocampal, without sclerosis), postinfectious encephalitic compared this Rasmussen encephalitis, Alzheimer disease, normal controls. Results could show cell were significantly elevated MTLE healthy numbers, however, varied highly among subgroups. By comparing GG sclerosis (HS), we able T-cell increased extrahippocampal neuronal loss HS, whereas cases (i.e., absence HS) did not differ from Importantly, correlated degree loss, no correlation seizure frequency disease duration found. Finally, found nearly all groups, remained even years after event. Significance provide detailed histopathological investigation MTLE, which suggests influx correlates rather than activity.