Abstract
To assess the role of interleukin（lL) -33 and ST2， the receptor fbr IL-33，in the pathogenesis of systemic
juvenile idiopathic arthritis（s-JIA）， we sequentially measured the seruln levels of IL-33 and soluble ST2（sST2）
in patients with s－JIA and deterlnined their correlation with measures of disease activity and severity．Twenty four
patients with s－J工A，5“）’ith rheumatoid factor positive polyarticular JIA（RF＋poly－JIA）， and 20 age－matched
healthy controls（HCs）were analyzed、 IL-33 and sST21evels were quantified in serum by enzyme-linked
immunosorbent assays． Serum IL-331evels in most patients with active s-JIA were below the lowest detection
limit． Serum IL-331evels in patients with RF+poly-JIA were much higher than those in patients with s-JIA and
HCs． Serum sST2 1evels in patients during the active phase of s-JIA were mutch higher than thosc ill patients
with poly-JIA and HCs． Serum sST2 1evels in patients with s-JIA were sjgnificantly elevated even in the inactive
phase， when other clinical parameters were normalized． Serum sST21evels correlated positively with the clinical
parameters of disease activity． These findings indicate that ST2 may be an important lnediator in s-JIA． Serum
sST2 1evels in patients with s-JIA correlated with disease activity， suggesting a potential role as a promising
indicator of disease activity．
