With regard to TREC numbers, no changes were observed in patients with JIA in remission at first evaluation (1649±586 per 104 CD4+CD28+CD45RA+ T cells) or after 12 months (1424±384 per 104 CD4+CD28+CD45RA+ T cells) (Figure 2B), while TREC number dramatically increased in our patient with acute exacerbation after 12 months (exacerbation: 737 per 104 CD4+CD28+CD45RA+ T cells; follow-up: 3749 per 104 CD4+CD28+CD45RA+ T cells) (Figure 2B). Here, CD4 is linked to juvenile idiopathic arthritis.