Immobilized and soluble Delta-1–FL reciprocally regulate c-Fms expression on adherent cells and immobilized Delta-1–FL, but do not affect the cell growth of BM cells.

(A) BM cells were cultured with M-CSF (50 ng/mL) for 4 days in dishes coated with Delta-1–FL, or BAP-FL, or in the presence of soluble Delta-1–FL (1 μg/mL) and then analyzed by flow cytometry. The shaded histograms represent staining with anti–Mac-1 and anti–c-Fms antibodies and the open histograms represent staining with a control antibody. (B) Total RNAs were prepared from dish-adherent BM cells cultured in the presence of immobilized Delta-1–FL or BAP-FL, or soluble Delta-1–FL, plus M-CSF (50 ng/mL) for 4 days. Serial dilutions (1:1, 1:9, 1:81) of cDNAs were subjected to PCR amplification specific for the c-Fms and Hprt genes. (C) Freshly prepared BM cells were cultured with M-CSF (50 ng/mL) on Delta-1–FL– or BAP-FL–coated dishes. After 2, 4, and 6 days of culturing, the numbers of dish-adherent and -nonadherent cells were counted.