Figure 1. GM-CSF regulates the phagocytosis of apoptotic cells.

(A) CFSE-labeled wild-type dying cells treated with dexamethasone (dex), etoposide, or necrotic cells were added to peritoneal macrophages, and phagocytosis was quantified by flow cytometry. Numbers refer to the percentage of cells within an indicated gate. (B) Purified splenic DCs or Flt3-L–derived bone marrow dendritic cells (BMDCs) were exposed to labeled apoptotic thymocytes, and phagocytosis was measured. (C) Peritoneal macrophages (3 mice per group) were loaded with apoptotic or necrotic thymocytes, and culture supernatants were measured by ELISA. (D) Peritoneal macrophages (circles, GM-CSF/IL-3/IFN-γ–deficient; squares, wild-type) were exposed to apoptotic (filled symbols) or necrotic (open symbols) thymocytes and cocultured with wild-type Balb/c splenocytes. Proliferation was determined by ³H-thymidine uptake. Results are representative of at least 2 or 3 independent experiments.