NOS2 and viral pneumonia: In the present study, the flow cytometry results revealed that QWJR diminished the ratio of CD86+/CD206+macrophages, decreased iNOS activity and increased Arg-1 expression level, indicating that QWJR could alleviate the inflammatory response of viral pneumonia by inhibiting the polarization of M1-type macrophages and promoting the polarization of M2-type macrophages.