In the below attached paper, the investigators isolated neutrophils from murine bone marrow by negative immunomagnetic isolation using a complex antibody cocktail. Most importantly, cells obtained by this method are non-activated and remain fully functional in vitro.
You should try this antibody cocktail which is able to isolate highly pure mature neutrophils which remain in a resting state during the isolation protocol.
Article Rapid Immunomagnetic Negative Enrichment of Neutrophil Granu...