Cd14 brilliantviolet 421

Neutrophils were stained for 20 min at RT with an antibody panel containing CD66b-FITC 1:20, CD10-PE-Cy7 1:20, CD11b-AlexaFluor 700 1:66, CD16-APC-H7 1:66, CD14-BrilliantViolet 421 1:66, Siglec8-BrilliantViolet 510 1:66 (all from BD) and CD62L-APC 1:66 (Biolegend). Neutrophils were washed and analyzed on a Cytoflex flow cytometer (Beckman Coulter).

For the analysis of the protein levels of selected ISGs (ISG15, PKR, and MX1), PBMCs were thawed at 37°C, counted, and seeded in a 96-well plate, and then analyzed directly or stimulated overnight at 37°C with or without IFN-α2b 40.000 IU/ml (Miltenyi Biotec). After stimulation, cells were labeled with a viability dye for 30 min at room temperature in PBS, followed by surface staining in PBS 2% FBS for 20 min at 4°C. Cells were then fixed and permeabilized using the FOXP3/Transcription Factor Fixation/Permeabilization Buffers (eBioscience) according to the instructions of the manufacturer. Fc Block (Human TruStain FcX, Biolegend) in PBS was used to prevent the unwanted binding of Fc receptor CD16 antibody. Finally, intracellular staining was performed for 30 min at room temperature in Permeabilization Buffer (eBioscience). The flow cytometry panel was the following: Viability Dye eFluor780 (65-0865-14, Invitrogen), CD14 Brilliant Violet 421 (563743, BD Biosciences), MXA Alexa Fluor 488 (AMab237298, Abcam), PKR Alexa Fluor 647 (AMab224921, Abcam), and ISG15 PE (IC8044P, R&D Systems).