Characterization of MGCs present in myeloma-DC cocultures. (A) Tumor cells were cocultured with immature DCs at a tumor/DC ratio of 1:100 in methylcellulose cultures. Cells were harvested for cytospins after an incubation of 2 weeks and stained for TRAP activity Shown is a representative TRAP + MGC (↑). Original magnification, ×40. (B-C) Bone resorption activity of MGCs present in tumor-DC cocultures. Cells from the methylcellulose cultures of tumor + DCs or DCs alone were cultured on Biocoat osteologic discs for 2 weeks. (B) Appearance of resorbed bone (pits) after Von Kossa staining is shown. Original magnification, ×10. (C) Quantification of resorbed osteologic discs or pit area by light microscopy. *P < .05.