The purpose of this study was to see if monocyte CD64 (mCD64) expression is connected to disease activity in individuals with adult-onset Still disease (AOSD) and if it can be utilized to differentiate between active and inactive disease phases. Researchers examined a group of ten individuals with a clear diagnosis of AOSD who were recruited between January 2013 and December 2016. They employed flow cytometry to quantify mCD64 expression levels in patients with active and inactive disease stages and then examined the accompanying changes statistically. mCD64 expression is much greater in the active condition than in the inactive state. To differentiate between active and inactive illness states, a receiver operating characteristic analysis with a cutoff value of 31,796.0 molecules/cell was used; the sensitivity and specificity were both 100%. Only mCD64 expression levels in these individuals altered in tandem with disease activity while receiving tocilizumab therapy; other conventional biomarkers evaluated showed no changes.

The expression of CD64 on monocytes might be utilized to distinguish between active and inactive AOSD. As a result, mCD64 may be a potential biomarker for assessing AOSD disease activity, even in patients undergoing tocilizumab therapy.