Femurs and tibias were obtained from 6-12 week old C57BL/6 mice. After euthanasia, the mice were sprayed with 70% ethanol and the femurs and tibias were dissected using scissors. Muscles connected to the bone were removed using scissors, and the femurs were placed into a 50 mL tube containing sterile DMEM on ice. In a tissue culture hood, the bones were washed in sterile DMEM and then both epiphyses were removed using sterile scissors and forceps. The bone marrow was flushed out with a 10 ml syringe filled with BM20 differentiation media (DMEM supplemented with 10% fetal bovine serum, 20% L929 supernatant, 5% horse serum, 100 U/ml penicillin, 100 mg/ml streptomycin, and 2 mM L-glutamine) (Life Technologies, Grand Island, NY) into a 50 mL sterile tube. The tube was vortexed gently and topped off to 50 mL with fresh BM20. 10 mL of cell suspension was plated out on 100 cm untreated dishes and incubated for 7 days at 37uC, 5% CO 2 with fresh media added at day 4. Cells were then washed, counted and plated at 10 6 cells/mL in BM10 media (DMEM supplemented with 10% fetal bovine serum 10% L929 supernatant, 5% horse serum, 100 U/ml penicillin, 100 mg/ml streptomycin, and 2 mM L-glutamine) (Life Technologies, Grand Island, NY) into a 50 mL sterile tube and allowed to rest for 3 days. Macrophages were stimulated overnight with either recombinant IL-4 (10 ng/ml), LPS (50 ng/ml) or IFN-c (100 U/ml) (all from R&D Systems, Minneapolis, MN), stAg (100 mg/ml) or cystAg (100 mg/ml) in complete DMEM.