Osteoclastogenic and bone-resorbing activity.
(A) Production of osteoclastogenic activity in 5TGM1 mouse myeloma cells and human myeloma cells cultured in rsVCAM-1–coated plates. Cells (1 × 106/mL/24-well) were cultured in plates coated with (closed bar) or without (open bar) rsVCAM-1 (1 μg/mL) in IMDM with 0.1% BSA for 24 hours. Conditioned media (40%) were assayed for osteoclastogenic activity in the mouse bone marrow cultures. Data are expressed as mean ± SE (n = 4). *Significantly different from control and conditioned media harvested from noncoated plates (P < .05). (B) Production of bone resorbing activity in 5TGM1 cells cultured in plates coated with rsVCAM-1. 5TGM1 cells (1 × 106/mL/24-well) were cultured in plates coated with or without rsVCAM-1 (1 μg/mL) in IMDM with 5% FBS for 24 hours. Conditioned media (40%) were assayed for bone-resorbing activity in organ cultures of 45Ca-labeled fetal rat long bones as described. Data are expressed as 45Ca release into the culture medium. Data are expressed as mean ± SE (n = 4). *Significantly different from conditioned medium of 5TGM1 myeloma cells cultured in noncoated plates (P < .01). (C) Effects of anti–VCAM-1 antibody (VCAM-1 Ab) or anti–α4β1-integrin antibody (α4β1 Ab) on the production of osteoclastogenic activity. 5TGM1 myeloma cells were cultured in rsVCAM-1–coated plates in the presence of 10 μg/mL of anti–VCAM-1 antibody (VCAM-1 Ab) or anti–α4β1-integrin antibody (α4β1 Ab) in IMDM with 5% FBS for 24 hours and conditioned medium (40%) was assayed for osteoclastogenic activity. Data are expressed as mean ± SE (n = 4). *Significantly different from conditioned medium of 5TGM1 cells cultured in noncoated plates (P < .01). **Significantly different from conditioned medium of 5TGM1 myeloma cells cultured in rsVCAM-1–coated plates without the antibodies (P < .01).
