Peripheral blood regulatory B and T cells are decreased in patients with focal epilepsy.

Patients with focal epilepsy of unknown cause (FEoUC) may display T cell infiltration in post-surgery brain specimens and increased serum levels of pro-inflammatory cytokines produced by B and T cells, indicating potential involvement of adaptive immunity. Our study aimed to investigate the peripheral blood distribution of B and T cell subgroups to find clues supporting the distinct organization of adaptive immunity in FEoUC. Twenty-two patients with FEoUC and 25 age and sex matched healthy individuals were included. Peripheral blood mononuclear cells were immunophenotyped by flow cytometry. Expression levels of anti-inflammatory cytokines and FOXP3 were measured by real-time PCR. Carboxyfluorescein succinimidyl ester (CFSE) proliferation assay was conducted using CD4 T cells. Patients with FEoUC showed significantly decreased regulatory B (Breg), B1a, plasmablast and regulatory T (Treg) cell percentages, and increased switched memory B and Th17 cell ratios. Moreover, CD4CD25CD49d Tregs of FEoUC patients displayed significantly reduced TGFB1 and FOXP3, but increased IL10 gene expression levels. CD4 helper T cells of patients with FEoUC gave more exaggerated proliferation responses to phytohemagglutinin, anti-CD3 and anti-CD28 stimulation. Patients with FEoUC display increased effector lymphocyte, decreased regulatory lymphocyte ratios, and impaired Treg function and enhanced lymphocyte proliferation capacity. Overall, this pro-inflammatory phenotype lends support to the involvement of adaptive immunity in FEoUC.