Abstracts

Rationale: The immune system is discussed to influence development and maintenance of epilepsies. Therefore we prospectively studied interictal changes of the immunoregulatory cytokines IL-1β, IL-6 and TNFα as well as changes in leukocyte subsets in patients with well-defined focal and idiopathic generalized epilepsies and aimed to detect modifying factors for these changes. Methods: In this prospective study, we included consecutive patients with clear-cut epileptic syndromes based on seizure semiology, interictal and ictal EEG recordings and high resolution MRI of the brain who were seen in the outpatients clinics and the monitoring unit of our epilepsy center. Patients were excluded if a seizure had occurred within 48 hours before the visit. Thirty-six healthy volunteers served as control group. Analyses of serum cytokines IL-6, IL-1β and TNFα were performed using sandwich ELISA (PeliKine-compact™, Sanquin Reagents, Amsterdam, The Netherlands). The analyses of the immune cell subset distribution in peripheral blood were performed by 4-color flow-cytometry (FACS). Non-parametric statistics were used for statistical comparisons. The significance level was set to p< 0.05. No adjustments for multiple testing were performed. Results: 113 patients were included (age: 37 ± 15 years, 72 female (64%); 87 (77%) with focal epilepsy, 26 (23%) with idiopathic generalized epilepsy; duration of epilepsy: 17±15 years, seizure frequency per month: 19 ±71). As compared to healthy controls, NK cells (12.8% vs. 9.4%, p=0.017) and monocytes (17.0% vs. 11.4%, p<0.001) were elevated and B lymphocytes (8.6% vs. 11.2%, p<0.001) decreased in the patient group. In addition, the patients showed elevated IL-6 concentrations (3.1 pg/ml vs. 1.5 pg/ml, p<0.001). Patients with idiopathic generalized epilepsy showed elevated B lymphocyte counts as compared to patients with focal epilepsy (8.2% vs. 10.2%, p=0.011). Within the patient group with focal epilepsies, patients suffering from hippocampal sclerosis revealed a decreased number of NK cells (12.2% vs. 15.3%, p=0.021) and an increased number of CD4+ lymphocytes (46.1% vs. 44.7%, p=0.02) as compared to the remainder of group suffering from other etiologies. Elevated IL-1β concentration was seen in patients with benign cerebral tumors or dysplasias (29.3 pg/ml vs. 12.75 pg/ml, p=0.005). We did not find any differences comparing the side of seizure onset or location of the epileptogenic zone (temporal versus extra-temporal).