We noticed that patients with AOSD had increased frequencies of T cells (81.08% (76.96; 87.78) vs. 72.53% (68.57; 73.88) with p = 0.007), while CD19+ B cells were decreased (5.32% (4.06; 9.97) vs. 12.54% (8.16; 16.13) with p = 0.018, respectively). This evidence concerns the gene CD19 and adult-onset Still disease.