Shimizu, T, Kikuchi-Taura, A, Tsuji, S, et al. - This study was attempted to evaluate whether monocyte CD64 (mCD64) expression is associated with disease activity in patients with adult-onset Still disease (AOSD) and whether it could be used to identify between active and inactive disease states. A total of 10 individuals with a definite diagnosis of AOSD, between January 2013 and December 2016 were included. Researchers applied flow cytometry to quantitatively estimate mCD64 expression levels in individuals presenting with active and inactive disease states and statistically analyzed the corresponding changes. The study's found that monocyte CD64 expression could be applied to clearly distinguish between active and inactive AOSD. Therefore, for evaluation of the disease activity of AOSD, mCD64 could be a promising biomarker, even in individuals receiving tocilizumab treatment.