The influence of levetiracetam and valproate on apoptosis and cytotoxic function of CD8+ T lymphocytes in vitro
Purpose: Previous studies showed that epilepsy patients treated with levetiracetam (LEV) had a higher incidence of upper respiratory tract infections and experimental and clinical data suggest also an immunomodulatory actions of valproate (VPA). The aim of this study was, therefore, to investigate t...
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|Summary:||Purpose: Previous studies showed that epilepsy patients treated with levetiracetam (LEV) had a higher incidence of upper respiratory tract infections and experimental and clinical data suggest also an immunomodulatory actions of valproate (VPA). The aim of this study was, therefore, to investigate the influence of LEV and VPA on apoptosis and cytotoxic function of CD8+ T lymphocytes in vitro.
Methods: After isolation of peripheral blood mononuclear cells (PBMCs) in 15 healthy subjects (9 female (60%), age: 35.7±12.1 years), apoptosis and cytotoxic function of CD8+ T lymphocytes were measured in vitro using immunofluorescence labeling and flow cytometry. Drug concentrations applied were 5mg/L and 50mg/L for LEV and 10mg/L and100mg/L for VPA, respectively. Apoptosis rates of CD8+ T lymphocytes were determined after incubation of PBMCs with LEV or VPA for 1h or 24h. Apoptotic CD8+ T lymphocytes were deifiined as CD3+/CD8+/ Annexin V+/PI- after applyingwiththe Annexin V Apoptosis Detection Kit® and flow cytometry. Perforin release, CD107a/b expression and proliferation of CD8+ T lymphocytes were measured within in the different groups following activation of CD8+ T lymphocytes with virus peptides, (which were made from cytomegalovirus, Epstein-Barr virus, and influenza virus; （CEF)）. Degranulation of CD8+ T lymphocyte was indicated by perforin release and the increase of CD107a/b expression on the cell surface. Group comparisons were performed with the paired t-test. T and the significance level was set to p<0.05.
Results: Both high (50mg/L) and low (5mg/L) concentrations of LEV decreased perforin release (LEV 50 mg/L vs controlCEF : 25.8±12.9% vs 18.2±9.7%, p<0.01; LEV 5mg/L vs control CEF: 24.1±13.7% vs 18.2±9.7%, p<0.01; n=15) and CD107a/b expression (LEV 50mg/L vs control CEF: 5.3±2.5% vs 11.5±4.7%, p<0.01; LEV 5mg/L vs control CEF: 6.7±2.2% vs 11.5±4.7%, p<0.01; n=15) of CD8+ T lymphocytes after 2h of virus-peptide induced stimulation. LEV had no influence on apoptosis and proliferation of CD8+ T lymphocytes (p﹥0.05). High concentration of VPA (100mg/L) prevented spontaneous apoptosis of CD8+ T lymphocytes after incubation for 24 h (VPA 100mg/L vs control: 7.8±3.4% vs 11.5±4.2%, p<0.01, n=15), but had no effects on perforin release or CD107a/b expression (p﹥0.05).
Conclusions: LEV showed a moderate attenuating effect on degranulation of CD8+ T lymphocytes which may contribute to the increased incidence of upper respiratory tract infections in LEV treated patients. Moreover, it is hypothesized that LEV‘s attenuating effect on perforin release adds to its anticonvulsant potency via reduction of inflammation in the epileptogenic zone and blood-brain-barrier disruption. Valproate revealed no effects onf the function of CD8+ T lymphocytes function but slowed apoptosis|