Assessment of TREM-1 expression in macrophages by flow cytometry.

To detect TREM-1 expression on the surface of macrophages, a total of 1 × 10⁶ RAW264.7 or primary peritoneal macrophages were washed with FACS buffer containing PBS with 2% FBS and stained with APC anti-mouse TREM-1 Ab (clone 174021, R&D Systems, Bio-Techne). Unstained cells were used as a negative control to establish the flow cytometer voltage setting. Acquisition was performed on 10,000 events using a BD LSRFortessa flow cytometer (BD Biosciences), and data were analyzed with FlowJo software (Tree Star).