PDCD1 and systemic-onset juvenile idiopathic arthritis: There was a negative correlation of the PD1 expression with markers of disease activity in sJIA.14 Decreased PB expression of PDL-1 in active sJIA patients compared to other febrile illnesses has also been described in a small study, although PB PD-L1 mRNA expression was upregulated.15 We found no significant differences regarding the PB PD1 expression between the different subtypes of JIA.