Interestingly, CD4+PD-1hiCXCL13+ T cells were also significantly increased in the SF of oligo JIA patients with disease onset at or before 6 years of age (13.8 ± 2.3%) compared to those who were older at the initial presentation of disease (5.8 ± 2.1%, p-value = 0.04) (Figure 2). This evidence concerns the gene CD4 and juvenile idiopathic arthritis.