Pretreatment of bone marrow-derived myeloid progenitors with NE inhibits granulocyte colony formation. Bone marrow mononuclear cells (BMMNC) isolated from four healthy donors were left untreated or treated with 1 μg/ml NE for 90 min at 37°C. The cells were then washed, resuspended in StemPro-34 serum-free media, and plated (1 × 104 cells) in serum-free Methocult containing 1% methylcellulose, G-CSF (20 ng/ml), and a cocktail of recombinant growth factors as described in the Materials and Methods. CFU-GM were enumerated after 14 days. Data are represented as the percent of CFU-GM colonies arising from NE-treated cells compared to untreated cells.