Phenotypic and functional dysregulations of CD8 + T Cells in myasthenia gravis.

Myasthenia Gravis (MG) is a heterogeneous autoimmune disorder characterized by fluctuating muscle weakness caused by autoantibodies targeting neuromuscular junction components. While the role of CD4 + T cells in MG is well established, the contribution of CD8 + T cells remains poorly understood. In this study, we analyze CD8 + T cells in 36 MG patients and 38 age- and gender-matched controls using flow cytometry to evaluate subset distribution, granzyme expression, and cytokine production. MG patients exhibit an altered CD4 + /CD8 + T cell ratio and significant changes in CD8 + T cell subsets, including increased central memory CD8 + T cell (Tcm) proportions and decreased effector memory CD8 + T cell (Tem) proportions. Granzyme B expression in Tcm cells is significantly elevated in MG patients, whereas no significant changes are observed in other subsets or GZMK expression. Cytokine analysis reveals increased IL-21, GM-CSF, and IL-17A production by CD8 + T cells in MG patients. These phenotypic and functional alterations of CD8 + T cells persist during the acute phase of the disease, regardless of immunotherapy usage, and vary between ocular and generalized MG. Subgroup and correlation analyses further identify age-dependent and age-independent dysregulations of CD8 + T cells, indicating complex and subtype-specific roles of CD8 + T cells in the immunopathological processes underlying MG. Our findings provide novel insights into the involvement of CD8 + T cells in MG pathogenesis, laying a foundation for future research and potential therapeutic strategies targeting CD8 + T cells.