Proportion of peripheral regulatory T cells in patients with autoimmune encephalitis

PURPOSE: Regulatory T cells (Tregs) play a crucial role in maintaining immune tolerance. Any deficiency or dysfunction of the Tregs can influence the pathogenesis of autoimmune disease. This study aimed to assess the role of Tregs among patients with autoimmune encephalitis (AE) with different autoantibody types and to evaluate their association with clinical features. METHODS: This was a cross-sectional observational study involving 29 patients with AE. Peripheral blood was sampled from each patient for flow cytometric analysis. Proportions of CD4(+)CD25(+) and CD4(+)CD25(+)Foxp3(+) Tregs were calculated and compared between the antibody types (synaptic, paraneoplastic, and undetermined). Associations between the proportion of Tregs and clinical features were also evaluated. RESULTS: Five patients had synaptic autoantibodies, five had paraneoplastic autoantibodies, and the others were of an undetermined type. The proportion of CD4(+)CD25(+) Tregs tended to be higher in those with paraneoplastic antibodies than in those with synaptic antibodies (post-hoc p = 0.028) and undetermined antibody status (post-hoc p = 0.043). A significant negative correlation was found between the proportion of Tregs and the initial modified Rankin score (r = −0.391, p = 0.036). Those who received intravenous immunoglobulin had lower proportions of Tregs than those who did not. CONCLUSION: The results of the present study suggest that Tregs may play different roles according to the type of AE and may be linked to disease severity.