Peripheral leukocyte profile in people with temporal lobe epilepsy reflects the associated proinflammatory state

Introduction: Markers of low-grade peripheral inflammation have been reported amongst people with epilepsy. The mechanisms underlying this phenomenon are unknown. We attempted to characterize peripheral immune cells and their activation status in people with temporal lobe epilepsy (TLE) and healthy controls. Methods and results: Twenty people with TLE and 19 controls were recruited, and peripheral blood lymphocyte and monocyte subsets evaluated ex vivo by multi-color flow cytometry. People with TLE had higher expression of HLA-DR, CD69, CTLA-4, CD25, IL-23R, IFN-γ, TNF and IL-17 in CD4⁺ lymphocytes than controls. Granzyme A, CTLA-4, IL-23R and IL-17 expression was also elevated in CD8⁺ T cells from people with TLE. Frequency of HLA-DR in CD19⁺ B cells and regulatory T cells CD4⁺CD25⁺Foxp3⁺ producing IL-10 was higher in TLE when compared with controls. A negative correlation between CD4⁺ expressing co-stimulatory molecules (CD69, CD25 and CTLA-4) with age at onset of seizures was found. The frequency of CD4⁺CD25⁺Foxp3⁺ cells was also positively correlated with age at onset of seizures. Conclusion: Immune cells of people with TLE show an activation profile, mainly in effector T cells, in line with the low-grade peripheral inflammation.