Increased expression of microRNA-21 in peripheral blood mediates the down-regulation of IFN-γ and increases the prevalence of stroke-associated infection.

•The SAI group had significantly higher plasma miRNA-21 and lower IFN-γ levels.•There was a significant negative correlation between plasma miRNA-21 and IFN-γ.•The optimal cutoff value was miRNA-21>0.53 and IFN-γ≤72.57pg/ml for predicting SAI.