Decreased PD-1 expression on circulating CD4+T cell and PD-L1 expression on myeloid dendritic cell correlate with clinical manifestations in systemic juvenile idiopathic arthritis

Abstract Objectives Programmed cell death-1 (PD-1) and its ligand (PD-L1) mediate negative signal in autoimmune diseases. While little is known about its role in juvenile idiopathic arthritis (JIA). The study aimed to reveal the circulating cell profile and the relative PD-1/PD-L1 expression of JIA subsets, elucidating their underlying immunomodulatory mechanisms. Methods We detected the circulating cells and the relative PD-1/PD-L1 signaling in 101 JIA patients and 50 controls by flow cytometry and analyzed their association with disease activity and clinical manifestations. Results Different from other JIA types, active systemic JIA (sJIA) patients had lower percentage and count of CD4 + T cells and lower PD-1 expression on them compared with healthy controls ( P P P P + T cell and PD-L1 on mDC were negatively correlated with JADAS-27 in sJIA patients ( P + T cell was negatively associated with the number of involved joints ( P P Conclusions Our finding displayed decreased CD4 + T cell, increased mDC and reduced PD-1/PD-L1 signal in sJIA PBMC comparing with other JIA subsets, which might be helpful in JIA differential diagnosis and responsible for distinct clinical manifestations via different mechanisms.