Cell culture. L929, RAW 264.7, and MEF cell lines were cultured in DMEM containing 10% FBS, glutamine, and penicillin-streptomycin. For bone marrow-derived macrophages, bone marrow cells from femurs and tibias were cultured for 7 d in RPMI 1640 media containing 10% FBS, glutamine, penicillin-streptomycin, and10% CSF from 3T3 cells, with feeding on the fourth day of growth. For conventional dendritic cells (GM-CSFdendritic cells), bone marrow cells were cultured for 5 d with RPMI 1640 containing 10% FBS, glutamine, penicillin-streptomycin, -mercaptoethanol, and GM-CSF, with fresh media added on the second and fourth days of growth. Peritoneal macrophages were elicited by injection of 2 ml 4% thioglycollate (Fluid Thioglycollate Medium; BD), and were obtained 4 d later by lavage of the peritoneal cavity with RPMI 1640.