CD19 and myasthenia gravis: Flow cytometry analysis demonstrated that the proportions of ABCs (CD19+CD11c+T-bet+), plasma cells (CD19+CD27+CD38+), and Tfh cells (CD4+PD-1+CXCR5+) in PBMCs were significantly elevated in the MG group compared to HC (p < 0.001 for all), whereas regulatory B cells (Bregs) (CD19+IL-10+) were significantly reduced (p < 0.0001; Figures 4A–H).